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Development of Combinatorial Pulsed Laser Deposition for Expedited Device Optimization in CdTe/CdS Thin-Film Solar Cells
摘要： A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 ??m to 0.75 ??m. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It is shown that the thinner CdTe layer of 0.75 ??m obtained the best power conversion efficiency up to 5.3%. The results of this work shows the importance that CdTe grain size/morphology relative to CdTe thickness has on device performance and quantitatively exhibits what those values should be to obtain efficient thin-film CdTe/CdS solar cells fabricated with pulsed laser deposition. Further development of this combinatorial approach could enable high-throughput exploration and optimization of CdTe/CdS solar cells.
关键词： combinatorial pulsed laser deposition,power conversion efficiency,grain morphology,CdTe/CdS thin-film solar cells,device optimization,crystal orientation
更新于2025-09-23 15:21:01
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Highly Efficient and Stable Pure 2D Perovskite Based Solar Cells with 3-Aminopropionitrile Organic Cation
摘要： Pure two-dimensional (2D) perovskite (n = 1) based perovskite solar cells (PSCs) have been proven to have excellent stability against humidity, but the photovoltaic performance is very poor due to the parallel orientation to the substrate and mismatched energy alignment in the PSC device. We report herein a novel bulky organic cation of 3-aminopropionitrile (3-APN) for constructing a pure 2D hybrid lead-iodide perovskite. The crystal structure of (3-APN)2PbI4 features a stable layered and undistorted PbI6 octahedral geometry ( ∠ Pb–I–Pb = 180o) with a small I···I distance (4.66 ?), and the crystals grow in a dominant out-of-plane direction to the substrate. In addition, the existence of intramolecular H-bond between cyano groups and ammonium heads result in an appropriate valence band level of (3-APN)2PbI4 for well-matched energy level alignment in the device, benefitting the interfacial charge transfer and hence better photovoltaic performance. As a result, the PSC with the pure 2D (3-APN)2PbI4 perovskite based PSC achieves power conversion efficiency of 3.39%, which is the highest value thus far for the pure 2D lead?iodide perovskite family, to the best of our knowledge. More importantly, this pure 2D (3-APN)2PbI4 perovskite based PSC demonstrates excellent stability against humidity. This work demonstrates that there is great potential to realize efficient and stable pure 2D perovskite based PSCs through the wise design of organic cations.
关键词： crystal orientation,3-aminopropionitrile,pure 2D,energy level alignment,perovskite solar cells
更新于2025-09-23 15:21:01
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Tin halide perovskite films made of highly oriented 2D crystals enable more efficient and stable lead-free perovskite solar cells
摘要： Low toxicity and an ideal energy bandgap make 2D Ruddlesden-Popper tin-based halide perovskites a promising photovoltaic material. However, the disordered crystal orientation and the oxidation of Sn2+ to Sn4+ still need to be addressed. Here, we demonstrate that the annealing of FASnI3 assisted by phenyl ethyl ammonium chloride enables the formation of more ordered 2D tin-based perovskite crystals oriented vertically. We use in-situ synchrotron-based grazing incident X-ray diffraction (GIXRD) to correlate the higher crystal orientation to the better device performance. We measured a maximum power conversion efficiency of >9%. Furthermore, we demonstrate that the phenyl ethyl ammonium chloride acts as a barrier layer at the surface of the crystals protecting the tin from the oxidation. Hence, this work paves the way for more efficient and stable lead-free perovskite solar cells.
关键词： phenyl ethyl ammonium chloride,photovoltaic material,crystal orientation,lead-free perovskite solar cells,oxidation of Sn2+,2D Ruddlesden-Popper tin-based halide perovskites,power conversion efficiency
更新于2025-09-23 15:21:01
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Nona??Preheating Processed Quasia??2D Perovskites for Efficient and Stable Solar Cells
摘要： Although the hot-casting (HC) technique is prevalent in developing preferred crystal orientation of quasi-2D perovskite films, the difficulty of accurately controlling the thermal homogeneity of substrate is unfavorable for the reproducibility of device fabrication. Herein, a facile and effective non-preheating (NP) film-casting method is proposed to realize highly oriented quasi-2D perovskite films by replacing the butylammonium (BA+) spacer partially with methylammonium (MA+) cation as (BA)2?x(MA)3+xPb4I13 (x = 0, 0.2, 0.4, and 0.6). At the optimal x-value of 0.4, the resultant quasi-2D perovskite film possesses highly orientated crystals, associated with a dense morphology and uniform grain-size distribution. Consequently, the (BA)1.6(MA)3.4Pb4I13-based solar cells yield champion efficiencies of 15.44% with NP processing and 16.29% with HC processing, respectively. As expected, the HC-processed device shows a poor performance reproducibility compared with that of the NP film-casting method. Moreover, the unsealed device (x = 0.4) displays a better moisture stability with respect to the x = 0 stored in a 65% ± 5% relative humility chamber.
关键词： solar cells,crystal orientation,quasi-2D perovskites,film casting
更新于2025-09-23 15:19:57
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A method for determining the orientation of [011] poled relaxor ferroelectric single crystal disks
摘要： A new method for determining the crystal orientation of [011] poled relaxor ferroelectric single crystal (RFSC) disks has been developed. This Technical Note describes the measurement techniques and mathematical approaches associated with this new method, which is possible due to the anisotropic response of [011] poled single crystal disks. Experimentally, the disks are subject to a distributed edge load at a series of angular orientations, with the output voltage recorded at each orientation. Equations have been developed to govern a particle swarm to find an optimised fit to the experimental data yielding the crystal orientation of the disk which is required for practical applications. Approximate values for the piezoelectric charge constants d31, d32 are also determined. The method is demonstrated on a RFSC Mn-PMN-PZ-PT disk, comparing favourably with a synchrotron x-ray transmission diffraction study on the same disk.
关键词： particle swarm,piezoelectric charge constant,crystal orientation,single crystal,relaxor ferroelectrics
更新于2025-09-19 17:13:59
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Fine Multi‐Phase Alignments in 2D Perovskite Solar Cells with Efficiency over 17% via Slow Post‐Annealing
摘要： Layered Ruddlesden–Popper (RP) phase (2D) halide perovskites have attracted tremendous attention due to the wide tunability on their optoelectronic properties and excellent robustness in photovoltaic devices. However, charge extraction/transport and ultimate power conversion efficiency (PCE) in 2D perovskite solar cells (PSCs) are still limited by the non-eliminable quantum well effect. Here, a slow post-annealing (SPA) process is proposed for BA2MA3Pb4I13 (n = 4) 2D PSCs by which a champion PCE of 17.26% is achieved with simultaneously enhanced open-circuit voltage, short-circuit current, and fill factor. Investigation with optical spectroscopy coupled with structural analyses indicates that enhanced crystal orientation and favorable alignment on the multiple perovskite phases (from the 2D phase near bottom to quasi-3D phase near top regions) is obtained with SPA treatment, which promotes carrier transport/extraction and suppresses Shockley–Read–Hall charge recombination in the solar cell. As far as it is known, the reported PCE is so far the highest efficiency in RP phase 2D PSCs based on butylamine (BA) spacers (n = 4). The SPA-processed devices exhibit a satisfactory stability with <4.5% degradation after 2000 h under N2 environment without encapsulation. The demonstrated process strategy offers a promising route to push forward the performance in 2D PSCs toward realistic photovoltaic applications.
关键词： crystal orientation,multi-phase alignments,slow post-annealing,quantum well effect,2D RP phase perovskites
更新于2025-09-19 17:13:59
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Single-grain growth in Si film by chevron-shaped cw laser beam scanning
摘要： A single grain with a length of 450 μm and a width of 5–6 μm was grown in a 60 nm Si ?lm on SiO2 by scanning a chevron-shaped cw laser beam, which was formed by passing a linear laser beam through a novel one-sided Dove prism. The crystal did not have any dominant orientations in both the growth and normal directions. The orientation rotated about the transverse direction at a rate of 0.47–0.51°/μm in the forward direction, which suggests that the lattice constant at the ?lm surface was 0.049–0.053% larger than that at the ?lm bottom.
关键词： crystal orientation,one-sided Dove prism,single-grain growth,chevron-shaped cw laser beam,Si film
更新于2025-09-19 17:13:59
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Tailoring the solar-blind photoresponse characteristics of ?2-Ga2O3 epitaxial films through lattice mismatch and crystal orientation
摘要： Realizing manipulation of the photoelectric properties of wide bandgap semiconductors is a main challenge for succeeding next-generation functional optoelectronics. As an intriguing wide bandgap semiconductor, β-Ga2O3 (Eg ~ 4.9 eV) is emerging as a promising candidate for photodetectors operating in solar-blind region. Here, we show that by selecting substrates with different symmetries and lattice parameters [i.e. (100) MgO, (100) MgAl2O4 and (0001) α-Al2O3], epitaxial β-Ga2O3 films with (100)- or (2?01)-oriented could be fabricated. We found that the photoresponse characteristics are strongly correlated with the lattice mismatch and film orientation. In particular, (100)-oriented β-Ga2O3 film grown on MgO substrate with smaller lattice mismatch exhibited a 254 nm responsivity of 0.1 A·W-1 and detectivity of 4.3×1012 Jones, which are approximately an order of magnitude higher than that of the (2?01)-oriented β-Ga2O3 film. Our work may provide a strategy to develop further high performance solar-blind photodetectors.
关键词： β-Ga2O3,crystal orientation,epitaxial films,lattice mismatch,solar-blind photodetectors
更新于2025-09-19 17:13:59