| 1. |
- Campanari, Valerio, et al.
(författare)
-
Reevaluation of Photoluminescence Intensity as an Indicator of Efficiency in Perovskite Solar Cells
- 2022
-
Ingår i: Solar RRL. - : John Wiley & Sons. - 2367-198X. ; 6:8
-
Tidskriftsartikel (refereegranskat)abstract
- The photoluminescence (PL) intensity is often used as an indicator of the performance of perovskite solar cells and indeed the PL technique is often used for the characterization of these devices and their constituent materials. Herein, a systematic approach is presented to the comparison of the conversion efficiency and the PL intensity of a cell in both open-circuit (OC) and short-circuit (SC) conditions and its application to multiple heterogeneous devices. It is shown that the quenching of the PL observed in SC conditions is a good parameter to assess the device efficiency. The authors explain the dependence of the PL quenching ratio between OC and SC on the cell efficiency with a simple model that is also able to estimate the carrier extraction time of a device.
|
|
| 2. |
- Yang, Bowen, et al.
(författare)
-
Interfacial Passivation Engineering of Perovskite Solar Cells with Fill Factor over 82% and Outstanding Operational Stability on n-i-p Architecture
- 2021
-
Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 6:11, s. 3916-3923
-
Tidskriftsartikel (refereegranskat)abstract
- Tremendous efforts have been dedicated toward minimizing the open-circuit voltage deficits on perovskite solar cells (PSCs), and the fill factors are still relatively low. This hinders their further application in large scalable modules. Herein, we employ a newly designed ammonium salt, cyclohexylethylammonium iodide (CEAI), for interfacial engineering between the perovskite and hole-transporting layer (HTL), which enhanced the fill factor to 82.6% and consequent PCE of 23.57% on the target device. This can be associated with a reduction of the trap-assisted recombination rate at the 3D perovskite surface, via formation of a 2D perovskite interlayer. Remarkably, the property of the 2D perovskite interlayer along with the cyclohexylethyl group introduced by CEAI treatment also determines a pronounced enhancement in the surface hydrophobicity, leading to an outstanding stability of over 96% remaining efficiency of the passivated devices under maximum power point tracking with one sun illumination under N-2 atmosphere at room temperature after 1500 h.
|
|
| 3. |
- Aryal, Um Kanta, et al.
(författare)
-
2D MXene-Based Electron Transport Layers for Nonhalogenated Solvent-Processed Stable Organic Solar Cells
- 2023
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 6:9, s. 4549-4558
-
Tidskriftsartikel (refereegranskat)abstract
- Implementation of 2D materials is one of the promising routes for improving the efficiency and stability of organic solar cells (OSCs). Due to their tunable optical and electronic properties, MXenes, a family of 2D transition metal carbides and nitrides, have attracted considerable attention and demonstrated their potential for next-generation solar cells. In this work, Ti3C2Tx MXene was added into ZnO precursors and applied as a modified composite electron transport layer (ETL) in PM6:N3-based inverted OSCs. The nonhalogenated solvent o-xylene was employed as the active layer solvent for the development of stable, efficient, and eco-friendly OSCs. By optimizing the concentration of Ti3C2Tx in the ZnO ETL, the solar cells exhibited power conversion efficiencies (PCEs) of 14.1 and 13.7% for 0.5 and 2 wt % MXene, respectively, as compared to neat ZnO layer devices with a PCE of 14.9%. Interestingly, the MXene-based PM6:N3 OSC devices showed superior device stability compared to the reference cells. It is demonstrated that the MXene introduced in the composite ZnO-based ETL mitigates the photocatalytic decomposition of the organic active layer on the ZnO surface, as analyzed via optical spectroscopy and hard X-ray photoelectron spectroscopy, which appears as a main reason for improved device stability. We thus report on the usage of MXene in green solvent-processed OSCs to enhance the lifetime of solar cells and thus address an important bottleneck in high-performance nonfullerene acceptor solar cells.
|
|
| 4. |
- Ellis, Hanna, 1985-
(författare)
-
Developing Environmentally Friendly Dye-sensitized Solar Cells
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to climate change and its effects, alternative renewable energy sources are needed in the future human society. In the work of this thesis, the Dye-sensitized Solar Cell (DSC) has been investigated and characterized.DSCs are appealing as energy conversion devices, since they have high potential to provide low cost solar light to electricity conversion. The DSC is built up by a working electrode consisting of a conductive glass substrate with a dye-sensitized mesoporous TiO2 film, a counter electrode with a catalyst and, in between, the electrolyte which performs the charge transport by means of a redox mediator. The aim of this thesis was to develop and evaluate cheap and environmentally friendly materials for the DSC.An alternative polymer-based counter electrode catalyst was fabricated and evaluated, showing that the PEDOT catalyst counter electrode outperformed the platinum catalyst counter electrode. Different organic dyes were evaluated and it was found that the dye architecture affected the performance of the assembled DSCs. A partly hydrophilic organic triphenylamine dye was developed and applied in water-based electrolyte DSCs. The partly hydrophilic dye outperformed the reference hydrophobic dye. Small changes in dye architecture were evaluated for two similar dyes, both by spectroscopic and electrochemical techniques. A change in the length of the dialkoxyphenyl units on a triphenylamine dye, affected the recombination and the regeneration electron transfer kinetics in the DSC system. Finally, three water soluble cobalt redox couples were developed and applied in water-based electrolyte DSCs. An average efficiency of 5.5% (record efficiency of 5.7%) for a 100% water-based electrolyte DSC was achieved with the polymer-based catalyst counter electrode and an organic dye with short dimethoxyphenyl units, improving the wetting and the regeneration process.
|
|
| 5. |
- Ishteev, Arthur, et al.
(författare)
-
Single source chemical vapor deposition (ssCVD) for highly luminescent inorganic halide perovskite films
- 2021
-
Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 119:7
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies of lead halide perovskites demonstrate outstanding optoelectronic properties for thin-film semiconductor device application. Perovskite photovoltaic and light-emitting diodes are on the way to the mass production and spread in commercial semiconductor devices. The lab-to-fab transition of perovskite devices requires adaptation of perovskite deposition methods to industrial semiconductor fabrication standards. In this work, we demonstrated the formation of highly luminescence perovskite films by single-source chemical vapor deposition (ssCVD). Several stoichiometry compositions were prepared from inorganic precursors of CsBr and PbBr2 by dry mechanochemical synthesis with following evaporation. The combination of mechanochemical synthesis and ssCVD is an attractive approach due to the ability to scale up to industrial level and the precise control over the evaporation rate with a single source. Among all compositions CsBr:PbBr2, we show that CsPb2Br5 maintains phase composition and photoluminescent properties for powder and film. This work provides a comparative study of evaporated film properties (PL, XRD, TEM) and modeling calculations of interphase optical transitions.
|
|
| 6. |
- Michaels, Hannes, 1994-
(författare)
-
A molecular guide to efficient charge transport : Coordination materials for photovoltaic cells
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Emerging solar energy conversion and energy storage technologies play a vital role in solving the present energy crisis and achieving carbon net zero. Currently, they are limited by the use of inefficient, unstable and expensive charge transport materials. The development of new charge transport materials is still far behind the efforts that have been made to develop the light-absorbing or other components. Metalorganic coordination compounds offer unique sets of properties as hybrids between conductive metals and tunable organic molecules. The coordination of the metal centers is crucial to control in order to maximise the solar cell efficiency - or undesired electronic recombination limits the power output. Tetradentate ligands allow copper complexes to dynamically switch between dimers or monomers, pending the oxidation state of the metal ions. The high energy barrier for the reduction of CuII monomers prevents electron transfer across the TiO2|dye|electrolyte interface: Interfacial recombination is reduced and the dye-sensitised solar cells achieve greater photovoltages. Coordination complexes linked into low-dimensional coordination polymers afford charge transport with an electrical conductivity as high as 0.1 S m-1 via band-like conduction at room temperature, needless of cationic dopants. The polymers rapidly extract photoexcited charges from halide perovskite films. 14% power conversion efficiency were recorded from a perovskite solar cell based on a carbon counter electrode. The solar cell stability was much increased compared to heavily doped organic hole conductors. Emerging dye-sensitised solar cells excel especially under ambient conditions, and have been proposed as power sources for dispatched electronic devices (the Internet of things), in place of single-use and difficult-to-recycle batteries. Through tailoring of the optical response and the electrolyte composition, power conversion efficiencies of 37.5% with photovoltages of 1.00 V at 1000 lux (fluorescent lamp) are demonstrated. The increased performance is identified to stem from reduced interfacial recombination by transient photovoltage methods as well as electrochemical impedance spectroscopy. A series of prototype tests underline the feasibility of light harvesters as power sources for electronic devices, executing sophisticated computation tasks such as machine learning. The devices self-optimise their energy consumption; adaptive sleep and small supercapacitors allow to sustain device operation during periods of fluctuating energy availability.
|
|
| 7. |
- Muratov, Dmitry S., et al.
(författare)
-
Slot-Die-Printed Two-Dimensional ZrS3 Charge Transport Layer for Perovskite Light-Emitting Diodes
- 2019
-
Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:51, s. 48021-48028
-
Tidskriftsartikel (refereegranskat)abstract
- Liquid-phase exfoliation of zirconium trisulfide (ZrS3) was used to produce stable and ready-to-use inks for solution-processed semiconductor thin-film deposition. Ribbon-like layered crystals of ZrS3 were produced by the chemical vapor transport method and were then exfoliated in three different solvents: dimethylformamide, ethanol, and isopropyl alcohol. The resulting ZrS3 dispersions were compared for stability and the ability to form continuous films on top of the perovskite layer in light-emitting diodes with the ITO/PEDOT:PSS/MAPbBr(3)/2D-ZrS3/LiF/Al structure. Film deposition was performed by using either spray or slot-die coating methods. The slot-die coating route proved to produce better and more uniform films with respect to spray coating. We found that the 2D ZrS3 electron injection layer (EIL) stabilized the interface between the perovskite and LiF/Al cathode, reducing the turn-on voltage to 2.8 V and showing a luminance that does not degrade during voltage sweep. On the other hand, ELL-free devices show electroluminescence on the first voltage sweep that reduces almost to zero in the subsequent sweeps. Combining physical device simulation and density functional theory calculation, we are able to explain these results in terms of lowering the electron injection barrier at the cathode.
|
|
| 8. |
|
|
| 9. |
- Ulisse, Giacomo, et al.
(författare)
-
Hybrid thermal-field emission of ZnO nanowires
- 2011
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:24
-
Tidskriftsartikel (refereegranskat)abstract
- The electron emission properties of an array of ZnO nanowires were studied in the temperature range of 300-473 K. An almost doubling of the current density at 473 K under an electric field of 8 V/μm (j (T=473 K) = 190 μA/cm 2, j (T=300 K) = 114 μA/cm 2) was observed together with a reduction of the turn-on field from 552 V/μm to 482 V/μm. Theoretical model that combines the thermal-field emission for high electric field and the Schottky emission for the low field can satisfactorily account for temperature dependence of current at low as well as at high applied bias. The obtained effect is particularly appealing for the application in micro-gun for THz vacuum tubes. © 2011 American Institute of Physics.
|
|
| 10. |
- Vesce, Luigi, et al.
(författare)
-
Hysteresis-Free Planar Perovskite Solar Module with 19.1% Efficiency by Interfacial Defects Passivation
- 2022
-
Ingår i: Solar RRL. - : John Wiley & Sons. - 2367-198X. ; 6:7
-
Tidskriftsartikel (refereegranskat)abstract
- In few years, perovskite solar devices have reached high efficiency on lab scale cells. Upscaling to module size, effective perovskite recipe and posttreatment are of paramount importance to the breakthrough of the technology. Herein this work, the development of a low-temperature planar n-i-p perovskite module (11 cm(2) aperture area, 91% geometrical fill factor) is reported on, exploiting the defect passivation strategy to achieve an efficiency of 19.1% (2% losses stabilized) with near-zero hysteresis, that is the most unsolved issue in the perovskite photovoltaic technology. The I/Br (iodine/bromide) halide ion ratio of the triple-cation perovskite formulation and deposition procedure are optimized to move from small area to module device and to avoid the detrimental effect of dimethyl sulfoxide (DMSO) solvent. The organic halide salt phenethylammonium iodide (PEAI) is adopted as surface passivation material on module size to suppress perovskite defects. Finally, homogeneous and defect-free layers from cell to module with only 8% relative efficiency losses, high reproducibility, and optimized interconnections are scaled by laser ablation methods. The homogeneity of the perovskite layers and of the full stack was assessed by optical, morphological, and light beam-induced current (LBIC) mapping characterizations.
|
|
