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Light Intensity-dependent Variation in Defect Contributions to Charge Transport and Recombination in a Planar MAPbI3 Perovskite Solar Cell
摘要： We investigated operation of a planar MApbi3 solar cell with respect to intensity variation ranging from 0.01 to 1 sun. Measured J-V curves consisted of space-charge-limited currents (SCLC) in a drift-dominant range and diode-like currents in a diffusion-dominant range. The variation of power-law exponent of SCLC showed that charge trapping by defects diminished as intensity increased, and that drift currents became eventually almost ohmic. Diode-like currents were analysed using a modified Shockley-equation model, the validity of which was confirmed by comparing measured and estimated open-circuit voltages. Intensity dependence of ideality factor led us to the conclusion that there were two other types of defects that contributed mostly as recombination centers. At low intensities, monomolecular recombination occurred due to one of these defects in addition to bimolecular recombination to result in the ideality factor of ~1.7. However, at high intensities, another type of defect not only took over monomolecular recombination, but also dominated bimolecular recombination to result in the ideality factor of ~2.0. These ideality-factor values were consistent with those representing the intensity dependence of loss-current ratio estimated by using a constant internal-quantum-efficiency approximation. The presence of multiple types of defects was corroborated by findings from equivalent-circuit analysis of impedance spectra.
关键词： perovskite solar cell,charge transport,defect contributions,recombination,light intensity-dependent variation
更新于2025-09-12 10:27:22
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A Machine‐Learning Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells
摘要： Organic solar cells (OSCs) based on ternary blend active layers are among the most promising photovoltaic technologies. To further improve the power conversion efficiency (PCE), the materials selection criteria must be focused on achieving high open-circuit voltage (Voc) through the alignment of the energy levels of the ternary blend active layers. Hence, machine-learning approaches are in high demand for extracting the complex correlation between Voc and the energy levels of the ternary blend active layers, which are crucial to facilitate device design. In the present work, the data-driven strategies are used to generate a model based on the available experimental data and the Voc are then predicted using available machine-learning methods (Random Forest regression and Support Vector regression). In addition, the Random Forest regression is compared with Support Vector regression to demonstrate the superiority of Random Forest regression for Voc prediction. The Random Forest regression is then developed to find the appropriate energy level alignment of ternary OSCs and to reveal the relationship between Voc and electronic features. Finally, an analysis based on the ranking of variables in terms of importance by the Random Forest model is performed to identify the key feature governing the Voc and the performance of ternary OSCs. From the perspective of device design, the machine-learning approach provides sufficient insights to improve the VOC and advances the comprehensive understanding of ternary OSCs.
关键词： organic field-effect transistors,Machine-learning,charge transport mobility.
更新于2025-09-12 10:27:22
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Watching Space Charge Build up in an Organic Solar Cell
摘要： A method is presented to spatially resolve the space charge region in organic photovoltaics (OPVs) by measuring white-light bias EQE and optical modeling. The method is demonstrated for a model polymer/fullerene blend with imbalanced carrier mobilities. Furthermore, numerical and analytical means are derived to discuss the general thickness limits for OPVs with imbalanced transport.
关键词： thick films,imbalanced charge transport,quantum efficiency,Organic photovoltaics,space charge
更新于2025-09-11 14:15:04
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Charge Transport and Extraction of Bilayer Interdiffusion Heterojunction Organic Solar Cells
摘要： Bilayer interdiffusion heterojunction with the structure of donor-rich region near the anode and acceptor-rich region near the cathode, could weaken energy level barrier between active layer and electrode, and improve the performance of organic solar cells. In this study, the poly (3-hexylthiophene) (P3HT) / [6:6]-phenyl-C61-butyric acid (PC61BM) bilayer interdiffusion heterojunction organic solar cells were prepared by using orthogonal solvent method, and the charge transport and extraction characteristics were investigated detailedly. The transient photovoltage/transient photocurrent measurements showed that the bilayer interdiffusion heterojunction devices have longer carrier recombination lifetime and shorter charge extract time, and higher carrier mobility of bilayer interdiffusion device was verified by photo-induced charge carrier extraction by linearly increasing voltage technology. The results indicated that the improved heterojunction structure of bilayer interdiffusion devices could reduce carrier recombination and improve charge transport and extraction efficiency. The performance of bilayer interdiffusion device was enhanced obviously, and about 19.8 % power conversion efficiency improvement was achieved as compared with the bulk device. Bilayer interdiffusion heterojunction provide an efficient device structure to optimize performance of organic solar cells.
关键词： Bilayer interdiffusion heterojunction,PC61BM,organic solar cells,P3HT,charge extraction,charge transport
更新于2025-09-11 14:15:04
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Charge Transport Behavior and Ultrasensitive Photoresponse Performance of Exfoliated F <sub/>16</sub> CuPc Nanoflakes
摘要： Air-stable, photosensitive copper hexadecafluorophthalocyanine (F16CuPc) is a promising n-type semiconductor for organic electronics and optoelectronics. However, the performance of F16CuPc-based devices is significantly limited by the poor crystallinity of thin films. Here, the charge transport and electrical contact behavior of F16CuPc nanoflakes, mechanically exfoliated from needle-like bulk single crystals, are probed by analyzing the temperature-dependent carrier mobility and conductance, where the multiple-trap/release- and band-like transport mechanism govern the charge transport at different temperature ranges and carrier densities. F16CuPc nanoflake-based field effect transistors (FETs) exhibit high on-state current and ON/OFF ratio, one-order magnitude higher than those of reported F16CuPc nanowires, thin films, and nanoribbons. Besides, F16CuPc nanoflake-based phototransistors exhibit attractive photoresponse performance in the spectral range of 300–750 nm even at quite low operating source–drain voltage (1 V), with maximum photoresponsivity of 19 A W?1, detectivity of 8 × 1012 Jones, and fast response speed of 36 ms, which is attributed to the single-crystalline characteristic of nanoflakes, and the resultant efficiently exciton diffusion and charge transport. The work demonstrates that 2D organic nanoflakes with single-crystalline feature will be promising candidates for flexible electronic and optoelectronic devices.
关键词： organic phototransistors,broadband photoresponse,charge transport,F16CuPc nanoflakes
更新于2025-09-11 14:15:04
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Improved Interface Charge Extraction by Double Electron Transport Layers for High‐Efficient Planar Perovskite Solar Cells
摘要： Charge extraction by electron transport layers (ETLs) plays a vital role in improving the performance of perovskite solar cells (PSCs). Here, PSCs with four different types of ETLs, such as SnO2, amorphous-Zn2SnO4 (am-ZTO), am-ZTO/SnO2, and SnO2/am-ZTO, are successfully synthesized. The interface recombination behavior and the charge transport properties of the devices affected by four types of ETLs are systematically investigated. For dual am-ZTO/SnO2 ETLs, compact am-ZTO ETL prepared by the pulsed laser deposition method provides a dense physical contact with FTO than the spin coating films, decreasing leakage current and improving charge collection at the interface of ETL/FTO. Moreover, dual am-ZTO/SnO2 ETLs lead to large free energy difference (ΔG), improving electron injection from perovskite to ETLs. One additional electron pathway from perovskite to am-ZTO is formed, which can also improve electron injection efficiency. A power conversion efficiency of 20.04% and a stabilized efficiency of 19.17% are achieved for the device based on dual am-ZTO/SnO2 ETLs. Most importantly, the devices are fabricated at a low temperature of 150 °C, which offers a potential method for large-scale production of PSCs, and paves the way for the development of flexible PSCs. It is believed that this work provides a strategy to design ETLs via controlling ΔG and interface contact to improve the performance of PSCs.
关键词： amorphous-Zn2SnO4/SnO2,charge transport,perovskite solar cells,interface recombination
更新于2025-09-11 14:15:04
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Electrochemically controlled CdS@CdSe nanoparticles on ITO@TiO2 dual core-shell nanowires for enhanced photoelectrochemical hydrogen production
摘要： Here, we report a novel dual heterostructured photoanode consisting of CdS@CdSe core-shell nanoparticles (NPs) and 1D-structure tin-doped indium oxide (ITO)@TiO2 core-shell nanowires (ITO@TiO2@CdS@CdSe) for highly efficient photoelectrochemical (PEC) hydrogen production. The finely controlled hierarchical core-shell CdS@CdSe sensitization from consecutive electrochemical deposition on the ITO@TiO2 core-shell nanowire has synergistic effects of visible-light utilization and efficient charge transport on the PEC response. The rationally designed dual core-shell heterostructure leads to cascade charge migration throughout the aligned energy band edges with rapid charge extraction through the hierarchical heterostructure of ITO@TiO2@CdS@CdSe, alleviating the crucial charge accumulation. As a result, the dual heterostructured photoanode exhibits a maximum photocurrent density of 20.11 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode (RHE) and a dramatic enhancement in the incident photon-to-current efficiency (IPCE) over the extended absorption spectrum. The time-resolved photoluminescence (TRPL) characterization indicates the realized multiple-band cascade charge migration throughout ITO@TiO2@CdS@CdSe could promote an 8-fold increase in the charge separation efficiency. This rational design of dual-heterojunction-structured photoelectrodes via electrochemical deposition provides a demonstration of modifying conventional light-harvesting photoelectrodes with stagnate solar energy conversion and PEC hydrogen production.
关键词： cascade charge transport,solar hydrogen production,electrochemical core-shell deposition,photoelectrochemical cell,dual heterostructure
更新于2025-09-11 14:15:04
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[Frontiers of Nanoscience] Nanostructured Thin Films Volume 14 || Spectroscopic and electrical properties of hybrid thin films for solar cell applications
摘要： Third-generation solar cells are designed in order to be able to fabricate thin film solar cells with solution deposition techniques and to obtain high-efficiency solar cells. There are two types of well-known solution-phase-fabricated solar cells: (1) multilayer structure and (2) bulk heterojunction (BHJ) solar cells. Multilayer structure solar cells are fabricated layer by layer of semiconductors, whereas BHJ solar cells consist of two semiconducting materials mixed in one common solvent and deposited onto a conductive glass substrate. Compared with multilayer structures, the BHJ method enables a reduction of the electron pathways between the two materials. One type of solution process for BHJ solar cells is the polymer-nanocrystal BHJ (or hybrid) solar cell. Hybrid BHJ solar cells are fabricated by blending the conducting polymer and inorganic colloidal NCs, and thus combining the properties of both organic and inorganic nanocrystals semiconductors. In this process, the performance of hybrid BHJ solar cells is influenced by the nanocrystals’ shape, solubility, and surface modification, as these properties are believed to affect the crystals’ incorporation in the polymer matrix.
关键词： bulk heterojunction,charge transport,ligand exchange,solar cells,nanocrystals,thin films,polymer
更新于2025-09-11 14:15:04
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Room-temperature quantum interference in single perovskite quantum dot junctions
摘要： The studies of quantum interference effects through bulk perovskite materials at the ?ngstrom scale still remain as a major challenge. Herein, we provide the observation of room-temperature quantum interference effects in metal halide perovskite quantum dots (QDs) using the mechanically controllable break junction technique. Single-QD conductance measurements reveal that there are multiple conductance peaks for the CH3NH3PbBr3 and CH3NH3PbBr2.15Cl0.85 QDs, whose displacement distributions match the lattice constant of QDs, suggesting that the gold electrodes slide through different lattice sites of the QD via Au-halogen coupling. We also observe a distinct conductance ‘jump’ at the end of the sliding process, which is further evidence that quantum interference effects dominate charge transport in these single-QD junctions. This conductance ‘jump’ is also confirmed by our theoretical calculations utilizing density functional theory combined with quantum transport theory. Our measurements and theory create a pathway to exploit quantum interference effects in quantum-controlled perovskite materials.
关键词： charge transport,quantum interference,room-temperature,mechanically controllable break junction,perovskite quantum dots
更新于2025-09-11 14:15:04
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Surface Modification for Improving the Photocatalytic Polymerization of 3,4-Ethylenedioxythiophene over Inorganic Lead Halide Perovskite Quantum Dots
摘要： Inorganic lead halide perovskite quantum dots (iLHP-QDs) have recently been used in the photocatalytic reaction. However, the factors that influence the photocatalytic performance of the iLHP-QDs has not been fully investigated. Herein, we synthesised a series of iLHP-QDs with varied halide ratio (CsPbX3, X=I, I0.67Br0.33, I0.5Br0.5, I0.33Br0.67, Br) and studied its influence on the photocatalytic performance by monitoring the polymerization of TerEDOT. The CsPbI3 QDs showed the best performance owing to its narrow bandgap and low exciton binding energy. Moreover, the photocatalytic performance of the iLHP-QDs could be simply improved by being treated with methyl acetate, which can be attributed to the replacement of the oleic acid by the short acetate acid, and the introduction of the traps on the surface of QDs in the post-treatment. These results could help design more efficient photocatalytic system and further promote the application of iLHP-QDs.
关键词： photocatalytic performance,quantum dots,exciton binding energy,charge transport efficiency,halide perovskite
更新于2025-09-11 14:15:04