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Role of surface recombination in perovskite solar cells at the interface of HTL/CH3NH3PbI3
摘要： In order to achieve the highest performance of organometal trihalide perovskite solar cells, it is required to recognize the dominant mechanisms which play a key role in a perovskite material. In the following studies, we have focused on the interfacial recombination between the hole transporting layer (HTL) and the perovskite CH3NH3PbI3 in solar cell devices with p–i–n architecture. It has been shown that Cu∶NiOx used as HTL drastically decreases a short–circuit photocurrent (Jsc) and an open–circuit voltage (Voc). However, we have found that an addition of PTAA thin layer improves cells quality and, as a consequence, the efficiency of such solar cells increases by 2%. Here, we explain both Jsc and Voc losses with a theory of the "dead layer" of perovskite material where a very high surface recombination occurs. We demonstrate the numerical and experimental studies by the means of series detailed analyses to get in–depth understanding of the physical processes behind it. Using a drift–diffusion model, it is shown that the presence of a parasitic recombination layer influences mostly the current distribution in the simulated samples explaining Jsc and Voc losses. The following results could be useful for improving the quality of perovskite solar cells.
关键词： dead layer recombination,perovskite solar cell,interface recombination
更新于2025-09-19 17:13:59
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Charge Carrier Collection and Contact Selectivity in Solar Cells
摘要： The electronic properties of the contacts to a photovoltaic absorber material are important for the final efficiency of any type of solar cell. For highly efficient solar cells based on high quality absorber materials like single-crystalline silicon, polycrystalline Cu(In,Ga)Se2, CdTe, or metal-halide perovskites, contact formation is even the decisive processing step determining the final efficiency. The present paper combines recently developed quantitative concepts for the description of contacts to solar cells in terms of their selectivity toward a more general description that is valid for all types of solar cells and all types of contacts. It is shown that the built-in voltage is an important parameter to influence the selectivity of contacts to photovoltaic absorber materials. It is also shown that the contact selectivity is mathematically related to the collection efficiency which can be measured by luminescence based techniques.
关键词： solar cells,charge extraction,surface recombination,photovoltaics,interface recombination
更新于2025-09-19 17:13:59
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Ba-induced phase segregation and band gap reduction in mixed-halide inorganic perovskite solar cells
摘要： All-inorganic metal halide perovskites are showing promising development towards efficient long-term stable materials and solar cells. Element doping, especially on the lead site, has been proved to be a useful strategy to obtain the desired film quality and material phase for high efficient and stable inorganic perovskite solar cells. Here we demonstrate a function by adding barium in CsPbI2Br. We find that barium is not incorporated into the perovskite lattice but induces phase segregation, resulting in a change in the iodide/bromide ratio compared with the precursor stoichiometry and consequently a reduction in the band gap energy of the perovskite phase. The device with 20 mol% barium shows a high power conversion efficiency of 14.0% and a great suppression of non-radiative recombination within the inorganic perovskite, yielding a high open-circuit voltage of 1.33 V and an external quantum efficiency of electroluminescence of 10?4.
关键词： inorganic perovskite solar cells,barium doping,non-radiative recombination,band gap reduction,phase segregation
更新于2025-09-19 17:13:59
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Niobium doped TiO2 nanorod arrays as efficient electron transport materials in photovoltaic
摘要： One-dimensional (1-D) rutile TiO2 nanorod arrays (NRAs) synthesized by a hydrothermal method suffer from low electrical conductivity and large amounts of surface defects, hindering their further applications. Nb doping is thus introduced to modify their electronic properties. Results indicate that light Nb doping reduces rod nanosizes, increases electron concentrations, decreases surface defective oxides and lowers conduction band of the TiO2 NRAs, while heavy doping induces transformations of morphologies and crystalline orientations as well as occurrences of compositional deviations and low oxidative states of Ti3t. After 0.1 mol% and 1 mol% Nb incorporations, device efficiencies are substantially improved by ~16% and ~33% for the model perovskite and dye-sensitized solar cells, respectively, which are ascribed to reduced recombination at the perovskite/TiO2 interfaces (e.g. charge lifetime increasing from 62 μs to 107 μs) and improved electron transport through the photoanode of TiO2 NRAs (e.g. electron diffusion length increasing from ~14 μm to ~50 μm). Our study verifies that Nb doped 1-D TiO2 NRAs are versatile electron transporting materials in different kinds of emerging solar cells, and are also potential for other fields including photocatalysis, sensors and batteries etc.
关键词： TiO2 nanorod array,Dye-sensitized solar cell,Niobium doping,Charge transport,Perovskite solar cell,Recombination
更新于2025-09-19 17:13:59
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Efficient Nanorod Arrays Perovskite Solar Cells: A Suitable Structure for High Strontium-Substitution in a Nature Environment
摘要： Organic-inorganic hybrid perovskite solar cells (PSCs) have become a research hotspot because of their excellent power conversion efficiency (PCE), but the presence of toxic lead (Pb) in perovskite film has significantly limited their commercial application. In this study, using a TiO2 nanorod arrays (TNRAs) as the electron transport layer (ETL), strontium chloride (SrCl2) was chosen to fabricate lead-less PSCs in air environment (relative humidity, RH=50%) by a simple two-step spin-coating method. The influence of introduced strontium (Sr) on the perovskite films and cell properties was systematically investigated by various characterization methods. With increasing Sr substitution amount from 0 to 15 mol%, the formed perovskite films with a compact structure and a large crystalline size essentially remained invariable, while residual PbI2 was reduced, which is beneficial for the cell performance. The optimal PCE of 16.08% (average PCE = 15.37%) was obtained for the 5 mol% Sr-substituted PSCs because of the enhanced charge extraction from the perovskite film to the TNRAs and the suppressed charge recombination in the PSC. Both the humidity and thermal stability of the Sr-substituted PSCs were improved. More importantly, the 15 mol% Sr-substituted PSCs still exhibited a PCE of 15.09% in air (RH = 50%), maintaining 99% of the cell efficiency of the pristine (0 mol% Sr) PSC (15.27%), suggesting that the TNRAs structure is suitable for synthesis of high Sr-substituted lead-less PSCs.
关键词： Lead-less perovskite solar cells,TiO2 nanorod arrays,Defect density,Strontium substitution,Recombination
更新于2025-09-19 17:13:59
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The effect of the recombination mechanisms location on the temperature sensitivity of thin-film photovoltaic cells
摘要： Thin film solar cells temperature sensitivity and impact of the main recombination mechanism location are investigated in this paper. The main mechanisms in bulk and at the heterojunction interface are discriminated. Using a 1D simulation software, “Solar Cell Capacitance Simulator” (SCAPS), we observed a higher temperature coefficient of open circuit voltage (Voc) for cells with main recombination centers at the interface than the one with main recombination centers in volume. Furthermore, an LTSpice module model is used to visualize the effects of the recombination centers’ location on the performance ratios of the modules. The results show more degradation for the ratios performance of cells with the main recombination mechanisms at the interface than those in volume.
关键词： recombination mechanisms,thin film cells,ratios performance,Temperature sensitivity
更新于2025-09-19 17:13:59
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Effect of annealing temperature on internal absorption, charge recombination and internal quantum efficiency of HC(NH2)2PbI3 perovskite solar cells
摘要： The effect of annealing temperature for the perovskite layer on the internal absorption(Q), charge recombination and internal quantum efficiency (IQE) of HC(NH2)2PbI3 (FAPbI3) perovskite solar cells (PeSCs) was investigated. The PeSC with FAPbI3 film annealed at 145 °C has relatively better internal absorption, lower charge recombination and higher charge collection, leading to the higher device IQE.
关键词： Charge recombination,Perovskite solar cell,Internal absorption,Internal quantum efficiency
更新于2025-09-19 17:13:59
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Understanding the Defect Properties of Quasi-2D Halide Perovskites for Photovoltaic Applications
摘要： Quasi-2D halide perovskites have emerged as one of the most promising photovoltaic materials owing to their excellent stability, yet the device power conversion efficiency (PCE) is far from satisfactory. Beside of crystal orientation related carrier transport, defects in absorbers also play a crucial role in device performance, which receives limited attention in the 2D perovskite field. Herein we systematically profiled the defects states in 2D perovskite film by the temperature-dependent admittance spectroscopy (AS), light-intensity-dependent VOC, space-charge-limited-circuit (SCLC), and photoluminescence measurements. It is revealed that the Quasi-2D perovskite films suffer from severe defects as compared to the 3D counterparts in terms of both trap energy levels and trap densities. Consequently, nonradiative recombination of photogenerated carriers is much greater in the corresponding devices, wherein the monomolecular recombination is dominant. These findings substantially benefit a deeper understanding of the nature of 2D perovskite materials, which promotes the further design of 2D perovskite solar cells.
关键词： carrier recombination,Quasi-2D halide perovskites,defects properties,photovoltaic materials,solar cells
更新于2025-09-19 17:13:59
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Incorporation of metal selenide thin films as the secondary absorber in the CdTe solar cells
摘要： The introduction of selenium in the CdTe solar cells has been responsible for high performance CdTe thin film solar cells in recent years. It is an approach to form CdSexTe1-x alloys by the interdiffusion using precursor CdSe layer during the CdTe high-temperature deposition process. Nevertheless, the compositionally gradient CdSexTe1-x formed by the diffusion makes it difficult to absorb long-wavelength photons adequately. So close-spaced sublimation deposited CdSexTe1-x interlayer was incorporated in the CdTe thin film solar cells. It is found that 600 nm CdSexTe1-x absorber is useful to increase long-wavelength photons absorption and extend the long-wavelength QE response. Meanwhile, the synergetic effects of the primary absorber deposition processing on CdTe solar cell performance were investigated. The substrate temperature of CdTe deposition has an obvious impact on the cell efficiency. The much higher substrate temperature can efficiently gain larger grain size, increase the crystal quality and promote the interdiffusion of different semiconductor layers. These improvements can efficiently decrease the carrier recombination to obtain a much higher fill factor and open-circuit voltage.
关键词： Spectral response,CdTe solar cells,Carrier recombination,CdSexTe1-x,CdSe
更新于2025-09-19 17:13:59
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Analysis of dominant non-radiative recombination mechanisms in InGaN green LEDs grown on silicon substrates
摘要： Relationship between the external quantum efficiency (EQE) curves and the dominant non-radiative recombination mechanisms of InGaN green LEDs grown on silicon substrates were investigated. Through the analysis of the ABC+(cid:1)(cid:2)(cid:3)(cid:4) model, the significant drop in EQE at low current levels is due to an increasingly defect-related Shockley-Read-Hall (SRH) recombination. Under extremely low current densities, the defect traps can even become the dominant channel for the leakage current through the tunneling process, thereby reducing the efficiency of carrier injection into the active region. These observations were further supported by the carrier lifetime measurement. However, this fails to explain the droop in EQE at high current densities, especially when SRH recombination has been saturated. Our results show that carrier leakage has becomes dominant at high current density when Auger recombination has been less impossible. Reduced carrier leakage may lead to increased carrier injection efficiency, which in turn alleviates EQE droop.
关键词： silicon substrates,InGaN,non-radiative recombination,green LEDs,external quantum efficiency,carrier leakage
更新于2025-09-19 17:13:59