| 1. |
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| 2. |
- Aartsen, M. G., et al.
(författare)
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Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube
- 2015
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 75:3
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Tidskriftsartikel (refereegranskat)abstract
- We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.
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| 3. |
- Aartsen, M. G., et al.
(författare)
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Search for Prompt Neutrino Emission from Gamma-Ray Bursts with IceCube
- 2015
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 805:1
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Tidskriftsartikel (refereegranskat)abstract
- We present constraints derived from a search of four years of IceCube data for a prompt neutrino flux from gammaray bursts (GRBs). A single low-significance neutrino, compatible with the atmospheric neutrino background, was found in coincidence with one of the 506 observed bursts. Although GRBs have been proposed as candidate sources for ultra-high-energy cosmic rays, our limits on the neutrino flux disfavor much of the parameter space for the latest models. We also find that no more than similar to 1% of the recently observed astrophysical neutrino flux consists of prompt emission from GRBs that are potentially observable by existing satellites.
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| 4. |
- Almora, Osbel, et al.
(författare)
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Device Performance of Emerging Photovoltaic Materials (Version 1)
- 2020
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Emerging photovoltaics (PVs) focus on a variety of applications complementing large scale electricity generation. Organic, dye-sensitized, and some perovskite solar cells are considered in building integration, greenhouses, wearable, and indoor applications, thereby motivating research on flexible, transparent, semitransparent, and multi-junction PVs. Nevertheless, it can be very time consuming to find or develop an up-to-date overview of the state-of-the-art performance for these systems and applications. Two important resources for recording research cells efficiencies are the National Renewable Energy Laboratory chart and the efficiency tables compiled biannually by Martin Green and colleagues. Both publications provide an effective coverage over the established technologies, bridging research and industry. An alternative approach is proposed here summarizing the best reports in the diverse research subjects for emerging PVs. Best performance parameters are provided as a function of the photovoltaic bandgap energy for each technology and application, and are put into perspective using, e.g., the Shockley–Queisser limit. In all cases, the reported data correspond to published and/or properly described certified results, with enough details provided for prospective data reproduction. Additionally, the stability test energy yield is included as an analysis parameter among state-of-the-art emerging PVs.
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| 5. |
- Christoforo, M. Greyson, et al.
(författare)
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Transient response of organo-metal-halide solar cells analyzed by time-resolved current-voltage measurements
- 2015
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Ingår i: Photonics. - : MDPI AG. - 2304-6732. ; 2:4, s. 1101-1115
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Tidskriftsartikel (refereegranskat)abstract
- The determination of the power conversion efficiency of solar cells based on organo-metal-halides is subject to an ongoing debate. As solar cell devices may exhibit very slow transient response, current-voltage scans in different directions may not be congruent, which is an effect often referred to as hysteresis. We here discuss time-resolved current-voltage measurements as a means to evaluate appropriate delay times (voltage settling times) to be used in current-voltage measurements of solar cells. Furthermore, this method allows the analysis of transient current response to extract time constants that can be used to compare characteristic differences between devices of varying architecture types, selective contacts and changes in devices due to storage or degradation conditions.
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| 6. |
- Dagar, Janardan, et al.
(författare)
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Alkali Salts as Interface Modifiers in n-i-p Hybrid Perovskite Solar Cells
- 2019
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 3:9
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Tidskriftsartikel (refereegranskat)abstract
- After demonstration of a 23% power conversion efficiency, a high operational stability is the next most important scientific and technological challenge in perovskite solar cells (PSCs). A potential failure mechanism is tied to a bias-induced ion migration, which causes current–voltage hysteresis and a decay in the device performance over time. Herein, alkali salts are shown to mitigate hysteresis and stabilize device performance in n-i-p hybrid planar PSCs. Different alkali salts of potassium chloride, iodide, and nitrate as well as sodium chloride and iodide are deposited from aqueous solution onto the n-type contact, based on SnO2, prior to deposition of the perovskite absorber Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3. Introduction of potassium-based alkali salts suppresses the current–voltage hysteresis and stabilizes the operational device stability at the maximum power point. This is attributed to the suppression of hole trapping at the n-type selective transport layer (SnO2)/perovskite interface observed by surface photovoltage spectroscopy, which is interpreted to reduce interfacial recombination and improve charge carrier extraction. The best and most stable performance of 19% is achieved using potassium nitrate as the interface modifier. Devices with higher and more stable performance exhibit substantially lower current transients, analyzed during maximum power point tracking.
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| 7. |
- Dagar, Janardan, et al.
(författare)
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Compositional and Interfacial Engineering Yield High-Performance and Stable p-i-n Perovskite Solar Cells and Mini-Modules
- 2021
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Ingår i: ACS applied materials & interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:11, s. 13022-13033
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Tidskriftsartikel (refereegranskat)abstract
- Through the optimization of the perovskite precursor composition and interfaces to selective contacts, we achieved a p-i-n-type perovskite solar cell (PSC) with a 22.3% power conversion efficiency (PCE). This is a new performance record for a PSC with an absorber bandgap of 1.63 eV. We demonstrate that the high device performance originates from a synergy between (1) an improved perovskite absorber quality when introducing formamidinium chloride (FACl) as an additive in the "triple cation" Cs0.05FA0.79MA0.16PbBr0.51I2.49 (Cs-MAFA) perovskite precursor ink, (2) an increased open-circuit voltage, VOC, due to reduced recombination losses when using a lithium fluoride (LiF) interfacial buffer layer, and (3) high-quality hole-selective contacts with a self-assembled monolayer (SAM) of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) on ITO electrodes. While all devices exhibit a high performance after fabrication, as determined from current-density voltage, J-V, measurements, substantial differences in device performance become apparent when considering longer-term stability data. A reduced long-term stability of devices with the introduction of a LiF interlayer is compensated for by using FACl as an additive in the metal-halide perovskite thin-film deposition. Optimized devices maintained about 80% of the initial average PCE during maximum power point (MPP) tracking for >700 h. We scaled the optimized device architecture to larger areas and achieved fully laser patterned series-interconnected mini-modules with a PCE of 19.4% for a 2.2 cm2 active area. A robust device architecture and reproducible deposition methods are fundamental for high performance and stable large-area single junction and tandem modules based on PSCs.
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| 8. |
- Dagar, Janardan, et al.
(författare)
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Stability assessment of p-i-n perovskite photovoltaic mini-modules utilizing different top metal electrodes
- 2021
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Long-term stability is one of the major challenges for p-i-n type perovskite solar modules (PSMs). Here, we demonstrate the fabrication of fully laser-patterned series interconnected p-i-n perovskite mini-modules, in which either single Cu or Ag layers are compared with Cu/Au metalbilayer top electrodes. According to the scanning electron microscopy measurements, we found that Cu or Ag top electrodes often exhibit flaking of the metal upon P3 (top contact removal) laser patterning. For Cu/Au bilayer top electrodes, metal flaking may cause intermittent short-circuits between interconnected sub-cells during operation, resulting in fluctuations in the maximum power point (MPP). Here, we demonstrate Cu/Au metal-bilayer-based PSMs with an efficiency of 18.9% on an active area of 2.2 cm2 under continuous 1-sun illumination. This work highlights the importance of optimizing the top-contact composition to tackle the operational stability of mini-modules, and could help to improve the feasibility of large-area module deployment for the commercialization of perovskite photovoltaics.
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| 9. |
- Dobrovolsky, Alexander, et al.
(författare)
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Defect-induced local variation of crystal phase transition temperature in metal-halide perovskites
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Solution-processed organometal halide perovskites are hybrid crystalline semiconductors highly interesting for low-cost and efficient optoelectronics. Their properties are dependent on the crystal structure. Literature shows a variety of crystal phase transition temperatures and often a spread of the transition over tens of degrees Kelvin. We explain this inconsistency by demonstrating that the temperature of the tetragonal-to-orthorhombic phase transition in methylammonium lead triiodide depends on the concentration and nature of local defects. Phase transition in individual nanowires was studied by photoluminescence microspectroscopy and super-resolution imaging. We propose that upon cooling from 160 to 140 K, domains of the crystal containing fewer defects stay in the tetragonal phase longer than highly defected domains that readily transform to the high bandgap orthorhombic phase at higher temperatures. The existence of relatively pure tetragonal domains during the phase transition leads to drastic photoluminescence enhancement, which is inhomogeneously distributed across perovskite microcrystals.
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| 10. |
- Dobrovolsky, Alexander, et al.
(författare)
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Relating Defect Luminescence and Nonradiative Charge Recombination in MAPbI3 Perovskite Films
- 2020
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 11:5, s. 1714-1720
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Tidskriftsartikel (refereegranskat)abstract
- Nonradiative losses in semiconductors are related to defects. At cryogenic temperatures, defect-related photoluminescence (PL) at energies lower than the band-edge PL is observed in methylammonium lead triiodide perovskite. We applied multispectral PL imaging to samples prepared by two different procedures and exhibiting 1 order of magnitude different PL quantum yield (PLQY). The high-PLQY sample showed concentration of the emitting defect sites around 1012-1013 cm-3. No correlation between PLQY and the relative intensity of the defect emission was found when micrometer-sized local regions of the same sample were compared. However, a clear positive correlation between the lower PLQY and higher defect emission was observed when two preparation methods were contrasted. Therefore, although the emissive defects are not connected directly with the nonradiative centers and may be spatially separated at the nano scale, chemical processes during the perovskite synthesis promote/prevent formation of both types of defects at the same time.
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| 11. |
- Fenske, Markus, et al.
(författare)
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Improved Electrical Performance of Perovskite Photovoltaic Mini-Modules through Controlled PbI2 Formation Using Nanosecond Laser Pulses for P3 Patterning
- 2021
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Ingår i: Energy Technology. - : Wiley. - 2194-4288 .- 2194-4296. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- The upscaling of perovskite solar cells to modules requires the patterning of the layer stack in individual cells that are monolithically interconnected in series. This interconnection scheme is composed of three lines, P1–P3, which are scribed using a pulsed laser beam. The P3 scribe is intended to isolate the back contact layer of neighboring cells, but is often affected by undesired effects such as back contact delamination, flaking, and poor electrical isolation. Herein, the influence of the laser pulse duration on the electrical and compositional properties of P3 scribe lines is investigated. The results show that both nanosecond and picosecond laser pulses are suitable for P3 patterning, with the nanosecond pulses leading to a higher open circuit voltage, a higher fill factor, and a higher power conversion efficiency. It is found that the longer pulse duration resultes in a larger amount of PbI2 formed within the P3 line and a thin Br-rich interfacial layer which both effectively passivate defects at the scribe line edges and block charge carrier in its vicinity. Thus, nanosecond laser pulses are preferable for P3 patterning as they promote the formation of beneficial chemical phases, resulting in an improved photovoltaic performance.
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| 12. |
- Gopakumar, Geethanjali, et al.
(författare)
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Probing aqueous ions with non-local Auger relaxation
- 2022
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:15, s. 8661-8671
-
Tidskriftsartikel (refereegranskat)abstract
- Non-local analogues of Auger decay are increasingly recognized as important relaxation processes in the condensed phase. Here, we explore non-local autoionization, specifically Intermolecular Coulombic Decay (ICD), of a series of aqueous-phase isoelectronic cations following 1s core-level ionization. In particular, we focus on Na+, Mg2+, and Al3+ ions. We unambiguously identify the ICD contribution to the K-edge Auger spectrum. The different strength of the ion-water interactions is manifested by varying intensities of the respective signals: the ICD signal intensity is greatest for the Al3+ case, weaker for Mg2+, and absent for weakly-solvent-bound Na+. With the assistance of ab initio calculations and molecular dynamics simulations, we provide a microscopic understanding of the non-local decay processes. We assign the ICD signals to decay processes ending in two-hole states, delocalized between the central ion and neighbouring water. Importantly, these processes are shown to be highly selective with respect to the promoted water solvent ionization channels. Furthermore, using a core-hole-clock analysis, the associated ICD timescales are estimated to be around 76 fs for Mg2+ and 34 fs for Al3+. Building on these results, we argue that Auger and ICD spectroscopy represents a unique tool for the exploration of intra- and inter-molecular structure in the liquid phase, simultaneously providing both structural and electronic information.
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| 13. |
- Grudin, Rebecca, et al.
(författare)
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“Therapy without a therapist?” The experiences of adolescents and their parents of online behavioural activation for depression with and without therapist support
- 2024
-
Ingår i: European Child and Adolescent Psychiatry. - : Springer Science and Business Media LLC. - 1018-8827 .- 1435-165X.
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Tidskriftsartikel (refereegranskat)abstract
- Behavioural Activation (BA) is an established treatment for adults with depression, and research on BA for adolescents is promising. However, there is a knowledge gap in terms of the experiences of adolescents and their parents BA for depression delivered online. Furthermore, there have been no previous studies conducted on the experiences of respondents with regard to the role of the therapist in online treatment. Therefore, the primary aim of this study is to explore the experiences of online BA among adolescents with depression and how their parents experience supporting their adolescent through treatment. Second, the experiences of having online therapy with or without a therapist were explored. Semi-structured interviews were conducted with eight adolescents and nine parents (n = 17) who completed guided or self-guided online BA. Reflexive thematic analysis was used to identify aspects of the experience of treatment that were important to adolescents and their parents. Two main themes were generated: (1) opportunities or barriers to engaging in treatment and (2) parental involvement is valued and welcomed. This study contributes valuable information regarding user experiences of BA treatment, the importance of therapist support and parental involvement in treating adolescents with depression. Trial registration number:ClinicalTrials.gov Identifier NCT04117789, Date of registration: 07 October 2019.
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| 14. |
- Haag, Tobias, et al.
(författare)
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Försurning och kalkning i Jönköpings län: verksamhetsberättelse 2007
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trots att svavelnedfallet har minskat med två tredjedelar sedan slutet av 1980-talet är nedfallet av försurande ämnen fortfarande över gränsen för vad marken beräknas tåla på sikt. I markvatten, som mäts på fyra lokaler i länet, saknas tydliga tecken på bättre förhållanden.För att uppnå miljömålen ”Bara naturlig försurning” och ”Levande sjöar och vattendrag” samt målet om ”God ekologisk status” i EU:s vattendirektiv behöver kalkningen fortsätta många år framöver.Kalkningen i länet berör hälften av länets yta men har störst omfattning i de sydvästra delarna. Ett minskat anslag för kalkning från Naturvårdsverket medförde ett intensivt revideringsarbete av alla kalkplaner i länet. Under 2007 spreds 12 700 ton kalk vilket är en minskning med 15 % jämfört med året innan. Under de senaste tio åren har kalkningen minskat med totalt 20 %.Arbetet med biologisk återställning har under 2007 inriktats på att öppna fiskvägar i några av Vätterns tillflöden vilket kommer att förbättra situationen för bland annat Vätteröringen som påverkats negativt av försurningen. Även i Nissan har fiskvägarna förbättrats vilket gynnar ett genuint strömstationärt öringbestånd.Den vattenkemiska måluppfyllelsen har undersökts på 347 lokaler i länet. För drygt 80 % av vattendragens längd och i 97 % av den sjöyta som undersökts var målet uppfyllt. Den biologiska måluppfyllelsen har generellt varit lägre än den vattenkemiska vilket är normalt. Under 2007 har målsättningen varit uppnådd i 49 % av vattendragens längd och 22 % av sjöytan vilket motsvarar 29 % av andelen sjöar. Den dåliga måluppfyllelsen beror på att sjöarna som nätprovfiskades under 2007 ligger i sydvästra delen av länet och är sjöar där biologisk återställning planeras.Enligt Naturvårdsverkets nya riktlinjer för hur ekologisk status ska bedömas, är endast hälften av de riksinventerade sjöarna försurade jämfört med vad tidigare bedömningsgrunder visade. Försurningsbedömning ska göras med MAGIC-modellen som modellerar fram vilket pH-värde en sjö hade 1860. Är pH-värdet idag mer än 0,4 pHenheter lägre än på 1800-talet så bedöms sjön som försurad. MAGIC-biblioteket är ett webbverktyg där man kan man hitta sjöar som är lik den sjö man är intresserad av och på så sätt försurningsbedöma sjön.Brunifiering är ett nytt begrepp som börjat användas under senare år i samband med att vattenfärgen i sjöar och vattendrag diskuteras. I de 13 tidsseriesjöar som finns inom eller nära de kalkade områdena i länet har vattenkemin studerats närmare. Svavelhalten har minskat i sjöarna men varken pH eller alkaliniteten (vattnets förmåga att stå emot syror) har ökat i motsvarande grad. Det har däremot den bruna färgen gjort. De humusämnen som ger vattnet dess bruna färg innehåller svaga organiska syror. Tidigare, under perioden med stort försurande nedfall, har dessa bundits i marken och inte nått vattnet. Nu när försurningen har minskat i såväl mark som vatten frigörs dessa ämnen och når sjöarna, vilket bromsar återhämtningen.
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| 15. |
- Hallgren Larsson, Eva, et al.
(författare)
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Kalkplan 2006 - Verksamhetsplan för kalkningsverksamheten
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Kalkplan 2006 omfattar verksamhetsplan för kalkningsverksamheten i Jönköpings län 2006 samt länets ansökan till Naturvårdsverket om medel för kalkning.Försurningen är länets största miljöproblem. I april 2001 beslutade Länsstyrelsens styrelse att försurningen fortfarande är ett av de åtgärdsområden som ska prioriteras i länets miljöarbete. Orsaken är hög belastning av försurande ämnen under lång tid. Länets västra och sydvästra delar är värst utsatta och stora delar klassas som mycket kraftigt försurningspåverkade. Trots att nedfallet av försurande svavel har minskat kraftigt i södra Sverige sedan slutet av 1980-talet kommer effekterna i mark och vatten sannolikt att kvarstå under lång tid och motivera kalkningsåtgärder under överskådlig tid. Kalkning är nödvändigt för att uppnå nationella och regionaliserade miljömål avseende "Levande sjöar och vattendrag" och "Bara naturlig försurning" samt målet om god ekologisk status enligt EUs ramdirektiv för vatten.Det övergripande långsiktiga målet för kalkningsverksamheten i Jönköpings län är att bevara och återskapa det naturliga växt- och djurlivet i ytvattnet som påverkats av antropogen försurning. Detta för att återställa och bibehålla biologisk mångfald så att den liknar de biologiska samhällen som fanns före den antropogena försurningen samt för att säkerställa ett långsiktigt nyttjande.Länets behov av kalkningsinsatser är stora och idag åtgärdas avrinningsområden motsvarande 50 % av länets yta. Cirka 700 sjöar och 150 vattendragsträckor är inordnade i 76 åtgärdsområden. Beräknat kalkningsbehov för 2006 är 15 539 ton. Verksamheten omfattar kalkningsåtgärder, effektuppföljning samt åtgärder för biologisk återställning.Kostnaden för kommunernas administration beräknas uppgå till 989 000 kronor under budgetåret 2006, varav bidragsdelen uppgår till 884 000 kronor. Länsstyrelsen anser att denna nivå är rimlig för att behålla nuvarande kvalitet på verksamheten.Länets behov av biologisk återställning är stora. Under 2006 planerar Länsstyrelsen att arbeta med vattendrag som bland annat har stor vikt för rekryteringen av öring till Vättern. För 2006 söker Länsstyrelsen medel för biotopvård och att åtgärda vandringshinder i Svedån och Knipån.Länsstyrelsen i Jönköpings län har behov av följande statsbidrag budgetåret 2006:Omkalkning 85 % bidrag: 8 361 000 kronorOmkalkning 100 % bidrag: 4 219 000 kronor Spridningskontroll: 216 000 kronorBiologisk återställningsåtgärder: 3 020 000 kronor Administration, kommuner: 884 000 kronorKemisk effektuppföljning: 881 000 kronorBiologisk effektuppföljning: 1 108 000 kronor Summa ansökt bidrag: 18 689 000 kronor
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| 16. |
- Hermerschmidt, Felix, et al.
(författare)
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Finally, inkjet-printed metal halide perovskite LEDs-utilizing seed crystal templating of salty PEDOT:PSS
- 2020
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Ingår i: Materials Horizons. - : Royal Society of Chemistry (RSC). - 2051-6347 .- 2051-6355. ; 7:7, s. 1773-1781
-
Tidskriftsartikel (refereegranskat)abstract
- Solution-processable metal halide perovskites are increasingly implemented in perovskite-based light-emitting diodes (PeLEDs). Especially green PeLEDs based on methylammonium lead bromide (MAPbBr3) composites exhibit impressive optoelectronic properties, while allowing processing by low-cost and upscalable printing methods. In this study, we have investigated the influence of potassium chloride (KCl) blended into the common hole injection material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to boost PeLED device performance. The inclusion of KCl firstly results in a change in morphology of the PEDOT:PSS layer, which then acts as a template during deposition of the perovskite layer. A MAPbBr3:polyethylene glycol (PEG) composite was used, which does not require the deposition of an anti-solvent droplet to induce preferential perovskite crystallization and is therefore suitable for spin coating and scalable inkjet printing processes. PeLEDs utilizing the KCl induced templating effect on a planar PEDOT:PSS/MAPbBr3:PEG architecture show improved performance, predominantly due to improved crystallization. PeLEDs incorporating spin-coated perovskite layers yield a 40-fold increase in luminance (8000 cd m-2) while the turn-on voltage decreases to 2.5 V. KCl-modified PEDOT:PSS contact layers enabled the realization of inkjet-printed PeLEDs with luminance increased by a factor of 20 at a maximum of 4000 cd m-2 and a turn-on voltage of 2.5 V. This work paves the way for inkjet-printed perovskite light-emitting devices for a wide variety of low-cost and customizable applications. This journal is
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| 17. |
- Jacobsson, Jesper, 1984-, et al.
(författare)
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An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
-
Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
-
Tidskriftsartikel (refereegranskat)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
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| 18. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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2-Terminal CIGS-perovskite tandem cells : A layer by layer exploration
- 2020
-
Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 207, s. 270-288
-
Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the development of 2-terminal CIGS-perovskite tandem solar cells by exploring a range of stack sequences and synthetic procedures for depositing the associated layers. In the end, we converged at a stack sequence composed of SLG/Mo/CIGS/CdS/i-ZnO/ZnO:Al/NiO/PTAA/Perovskite/LiF/PCBM/SnO2/ITO. With this architecture, we reached performances only about 1% lower than the corresponding 4-terminal tandem cells, thus demonstrating functional interconnects between the two sub-cells while grown monolithically on top of each other. We go through the stack, layer-by-layer, discussing their deposition and the results, from which we can conclude what works, what does not work, and what potentially could work after additional modifications. The challenges for a successful 2-terminal tandem device include: how to deal with, or decrease, the surface roughness of the CIGS-stack, how to obtain uniform coverage of the layers between the CIGS and the perovskite while also obtaining a benign interface chemistry, and how to tune the band gaps of both the CIGS and the perovskite to obtain good optical matching. The investigation was based on CIGS with a power conversion efficiency around 14%, and perovskites with an efficiency around 12%, resulting in 2-terminal tandem cells with efficiencies of 15–16%. The results indicate that by using higher performing CIGS and perovskite sub-cells, it should be possible to manufacture highly efficient 2-terminal CIGS-perovskite tandem devices by using the protocols, principles, and procedures developed and discussed in this paper.
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| 19. |
- Johansson, Erik M. J., et al.
(författare)
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Efficient infiltration of low molecular weight polymer in nanoporous TiO2
- 2011
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 502:4-6, s. 225-230
-
Tidskriftsartikel (refereegranskat)abstract
- The polymer APFO(3) was prepared with different molecular weights to study how the infiltration into nanoporous TiO2 films of different thickness depends on the size of the polymer. Also two different sizes of TiO2 nanoparticles were investigated to understand the effect of different pore size. It was observed that the lowest molecular weight polymer dissolved in chlorobenzene could infiltrate the nanoporous TiO2 network up to several micrometer thick films. It was concluded that efficient polymer infiltration into thick nanoporous layers was possible for the polymers with an estimated average chain length smaller than the diameter of the nanoparticles.
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| 20. |
- Kegelmann, Lukas, et al.
(författare)
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It Takes Two to Tango - Double-Layer Selective Contacts in Perovskite Solar Cells for Improved Device Performance and Reduced Hysteresis
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:20, s. 17245-17255
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Tidskriftsartikel (refereegranskat)abstract
- Solar cells made from inorganic-organic perovskites have gradually approached market requirements as their efficiency and stability have improved tremendously in recent years. Planar low-temperature processed perovskite solar cells are advantageous for possible large-scale production but are more prone to exhibiting photocurrent hysteresis, especially in the regular n-i-p structure. Here, a systematic characterization of different electron selective contacts with a variety of chemical and electrical properties in planar n-i-p devices processed below 180 °C is presented. The inorganic metal oxides TiO2 and SnO2, the organic fullerene derivatives C60, PCBM, and ICMA, as well as double-layers with a metal oxide/PCBM structure are used as electron transport materials (ETMs). Perovskite layers deposited atop the different ETMs with the herein applied fabrication method show a similar morphology according to scanning electron microscopy. Further, surface photovoltage spectroscopy measurements indicate comparable perovskite absorber qualities on all ETMs, except TiO2, which shows a more prominent influence of defect states. Transient photoluminescence studies together with current-voltage scans over a broad range of scan speeds reveal faster charge extraction, less pronounced hysteresis effects, and higher efficiencies for devices with fullerene compared to those with metal oxide ETMs. Beyond this, only double-layer ETM structures substantially diminish hysteresis effects for all performed scan speeds and strongly enhance the power conversion efficiency up to a champion stabilized value of 18.0%. The results indicate reduced recombination losses for a double-layer TiO2/PCBM contact design: First, a reduction of shunt paths through the fullerene to the ITO layer. Second, an improved hole blocking by the wide band gap metal oxide. Third, decreased transport losses due to an energetically more favorable contact, as implied by photoelectron spectroscopy measurements. The herein demonstrated improvements of multilayer selective contacts may serve as a general design guideline for perovskite solar cells.
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| 21. |
- Kiligaridis, Alexander, et al.
(författare)
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Excitation wavelength dependence of photoluminescence flickering in degraded MAPbI3 perovskite and its connection to lead iodide formation
- 2020
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Ingår i: Journal of Luminescence. - : Elsevier BV. - 0022-2313. ; 222
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskite semiconductors often exhibit photoluminescence blinking and flickering when luminescence of individual small nano- or even microcrystals is monitored. The nature of these fluctuations is not well understood but must be related to the presence of metastable non-radiative recombination channels and efficient charge migration in these materials. Here we report on the excitation wavelength dependence of photoluminescence flickering effect in degraded methylammonium lead iodide (MAPbI3) thin films. While the luminescence intensity is temporary stable when excited in the blue region with wavelength shorter than 530 nm, excitation with red light (wavelength longer than 530 nm) results in luminescence flickering. It is hypothesised that the wavelength dependence reflects the excitation energy dependence of the photochemical mechanism that switches non-radiative recombination channels on and off. The effect can also be related to hindered charge carrier diffusion due to their localization in the interfacial layer between MAPbI3 and PbI2 which is formed in the course of degradation.
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| 22. |
- Kirchartz, Thomas, et al.
(författare)
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Research Update : Recombination and open-circuit voltage in lead-halide perovskites
- 2018
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Ingår i: APL Materials. - : AIP Publishing. - 2166-532X. ; 6:10
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Tidskriftsartikel (refereegranskat)abstract
- The high open-circuit voltage and the slow recombination in lead-halide perovskite solar cells has been one of the main contributors to their success as photovoltaic materials. Here, we review the knowledge on recombination in perovskite-based solar cells, compare the situation with silicon solar cells, and introduce the parameters used to describe recombination and open-circuit voltage losses in solar cells. We first discuss the effect of lifetimes and surface recombination velocities on photovoltaic performance before we study the microscopic origin of charge-carrier lifetimes. The lifetimes depend on defect positions and densities and on the kinetic prefactors that control the phonon-assisted interaction between the extended states in the conduction and valence band and the localized defect states. We finally argue that the key to understand the long lifetimes and high open-circuit voltages is a combination of a low density of deep defects and a slow dissipation of energy via multiphonon processes due to the low phonon energies in the lead-halide perovskites.
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| 23. |
- Li, Jinzhao, et al.
(författare)
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20.8% Slot-Die Coated MAPbI3 Perovskite Solar Cells by Optimal DMSO-Content and Age of 2-ME Based Precursor Inks
- 2021
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Solar cells incorporating metal-halide perovskite (MHP) semiconductors are continuing to break efficiency records for solution-processed solar cell devices. Scaling MHP-based devices to larger area prototypes requires the development and optimization of scalable process technology and ink formulations that enable reproducible coating results. It is demonstrated that the power conversion efficiency (PCE) of small-area methylammonium lead iodide (MAPbI3) devices, slot-die coated from a 2-methoxy-ethanol (2-ME) based ink with dimethyl-sulfoxide (DMSO) used as an additive depends on the amount of DMSO and age of the ink formulation. When adding 12 mol% of DMSO, small-area devices of high performance (20.8%) are achieved. The effect of DMSO content and age on the thin film morphology and device performance through in situ X-ray diffraction and small-angle X-ray scattering experiments is rationalized. Adding a limited amount of DMSO prevents the formation of a crystalline intermediate phase related to MAPbI3 and 2-ME (MAPbI3-2-ME) and induces the formation of the MAPbI3 perovskite phase. Higher DMSO content leads to the precipitation of the (DMSO)2MA2Pb3I8 intermediate phase that negatively affects the thin-film morphology. These results demonstrate that rational insights into the ink composition and process control are critical to enable reproducible large-scale manufacturing of MHP-based devices for commercial applications.
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| 24. |
- Li, Jun, et al.
(författare)
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Luminescent Intermediates and Humidity-Dependent Room-Temperature Conversion of the MAPbI3 Perovskite Precursor
- 2018
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 3:10, s. 14494-14502
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Tidskriftsartikel (refereegranskat)abstract
- Preparation of metal-halide perovskites under room temperature attracts attention because of energy saving by removing thermal annealing. Room-temperature transformation of spin-cast wet films consisting of methylammonium (MA) iodide, PbI2, and dimethylformamide toward solid MAPbI3 perovskite proceeds via several intermediate crystalline states and is strongly dependent on ambient humidity. Light transmission and photoluminescence (PL) microscopy and spectroscopy were used to monitor the growth of crystals and transformation of their properties in time under nitrogen atmosphere at room temperature. Under low humidity, a highly luminescent intermediate phase with low absorption in the visible range appears, with the PL spectra composed of several bands in the range from 600 to 760 nm. We assign these bands to low-dimensional (nanocrystals and two-dimensional inclusions) MAPbI3 intermediates, where the exciton confinement shifts the spectrum to higher energies in comparison with the bulk MAPbI3. The intermediate levels of ambient humidity (10-50%) appear to catalyze the conversion of the intermediate phase to MAPbI3. At a high ambient humidity (>80%), the initially formed MAPbI3 is quickly transformed to the transparent hydrate phase of MAPbI3. The role of ambient water catalyzing the material transformation by competing for Pb coordination with the solvent molecules is discussed.
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| 25. |
- Li, Jun, et al.
(författare)
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Tolerance of metal halide perovskites to mechanical treatment enables the fabrication of patterned luminescence nano- and microstructures
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 27:35
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites have shown a great performance in a broad range of optoelectronic devices. The variety of preparation methods makes perovskites especially attractive, yet preparation of complex nanostructures based on these materials remains challenging. Here we present a template assisted method allowing to achieve any pre-designed arrangement of methylammonium lead triiodide (MAPbI3) polycrystalline patterns with the spatial resolution defined by the template. We utilized a Si/SiO2 wafer with circular 180 nm deep recesses with diameters ranging from 200 to 1600 nm as a template. A polycrystalline perovskite powder was obtained by scratching off a thin perovskite film and mechanically introduced into the patterned template as a pigment. Scanning electron microscopy revealed that the recesses are filled with tightly packed sub-20 nm crystallites. Considering that the spin-coated film used as a source of MAPbI3 consisted of grains up to 2000 nm in diameter suggests that the initially prepared grains were crashed by rubbing to much smaller crystallites. In spite of this harsh mechanical treatment, the filled recesses showed a strong photoluminescence signal, demonstrating the applicability of this approach for the fabrication of diverse nanophotonic structures.
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