| 1. |
- Dagar, Janardan, et al.
(author)
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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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In: ACS applied materials & interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:11, s. 13022-13033
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Journal article (peer-reviewed)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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| 2. |
- Li, Jinzhao, et al.
(author)
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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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In: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 11:10
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Journal article (peer-reviewed)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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| 3. |
- Schorr, Susan, et al.
(author)
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X-ray and Neutron Diffraction on Materials for Thin-Film Solar Cells
- 2016. - 2
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In: Advanced Characterization Techniques for Thin Film Solar Cells. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 9783527699025 - 9783527339921 ; , s. 421-440
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Book chapter (peer-reviewed)abstract
- Among the various experimental methods, neutron and X-ray scattering have become key techniques of choice. While neutron scattering provides insights into the crystal structure with high resolution, X-ray scattering has the advantage that measurement durations are usually much shorter, compared with neutron scattering. The analysis of preferred orientations in thin films is important since it almost invariably arises as a consequence of the processes of crystallizations and recrystallizations or sintering during the growth processes of the thin films. XRD from randomly oriented polycrystalline thin films often suffers from low peak intensity and poor peak to background ratio for symmetrical XRD measurements such as Θ-2Θ powder diffraction techniques. To be able to improve the situation for weakly diffracting thin films, low-angle XRD techniques such as grazing incidence X-ray diffraction (GIXRD) have been developed. The microstructural analysis of polycrystalline thin films is performed by conducting a Le Bail analysis.
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| 4. |
- Shargaieva, Oleksandra, et al.
(author)
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Temperature-Dependent Crystallization Mechanisms of Methylammonium Lead Iodide Perovskite From Different Solvents
- 2021
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In: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 9
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Journal article (peer-reviewed)abstract
- Hybrid perovskites are a novel type of semiconductors that show great potential for solution-processed optoelectronic devices. For all applications, the device performance is determined by the quality of the solution-processed perovskite thin films. During solution processing, the interaction of solvent with precursor molecules often leads to the formation of solvate intermediate phases that may diverge the crystallization pathway from simple solvent evaporation to a multi-step formation process. We here investigate the crystallization of methylammonium lead iodide (MAPbI3) from a range of commonly utilized solvents, namely dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and gamma-butyrolactone (GBL) at different temperatures ranging from 40°C to >100°C by in-situ grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. For all solvents but GBL, we clearly observe the formation of solvate-intermediate phases at moderate processing temperatures. With increasing temperatures, an increasing fraction of the MAPbI3 perovskite phase is observed to form directly. From the temperature-dependence of the phase-formation and phase-decomposition rates, the activation energy to form the MAPbI3 perovskite phase from the solvate-phases are determined as a quantitative metric for the binding strength of the solvent within the solvate-intermediate phases and we observe a trend of DMSO > DMF > NMP > GBL. These results enable prediction of processing temperatures at which solvent molecules can be effectively removed.
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