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Simulation of perovskite solar cell temperature under reverse and forward bias conditions
摘要： We have developed a model to calculate the temperature of an illuminated perovskite solar cell (PSC) under the forward bias and that of a shaded one under the reverse bias at di?erent ambient conditions. The results show that the dissipated power due to the reverse bias (PRB) should be more than around 6 W to have a higher temperature in the shaded solar cell than that in the illuminated solar cell at the solar irradiance of 1000 W=m2, and this result is almost ambient temperature and wind velocity independent. It is also found that the generated thermal power due to the nonradiative recombination (PRec) becomes signi?cant at the open circuit voltage (Voc) condition, leading to illuminated solar cell temperature (Tcr) higher than that at the short circuit current (Jsc) condition by about 12.7 K, 13.3 K, and 13.9 K at the ambient temperatures of 270 K, 300 K, and 330 K, respectively. In addition, the in?uence of the thickness of the illuminated solar cell on its temperature at the Voc condition is investigated, which reveals that, by increasing the thickness from 100 nm to 300 nm, the solar cell temperature can increase by 20 K.
关键词： temperature,nonradiative recombination,perovskite solar cell,reverse bias,forward bias
更新于2025-09-19 17:13:59
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Soft Lattice and Defect Covalency Rationalize Tolerance of ?2a??CsPbI3 Perovskite Solar Cells to Native Defects
摘要： Although all-inorganic lead halide perovskite solar cells have shown tremendous improvement over the past few years, they are still inferior to the hybrid organic-inorganic perovskites in the solar power conversion efficiency. Recently, a conceptually new β-CsPbI3 perovskite has demonstrated an impressive 18.4% efficiency combined with good thermodynamic stability at ambient conditions. We use ab initio non-adiabatic molecular dynamics to show that native point defects in β-CsPbI3 are generally benign for nonradiative charge recombination, regardless of whether they introduce shallow or deep trap states. Moreover, formation of new covalently bound species in the presence of defects slows down the recombination. These results indicate that halide perovskites do not follow the simple models used to explain defect-mediated charge recombination in the conventional semiconductors. The strong tolerance of electron-hole recombination against defects arises due to the softness of the perovskite lattice, which permits separation of electrons and holes upon defect formation, and allows only low-frequency vibrations to couple to the electronic subsystem. Both factors decrease significantly the non-adiabatic coupling and slow down the dissipation of electronic energy to heat. We suggest that a halide-rich synthesis environment may further improve the efficiency, and propose that strong defect tolerance is general to metal halide perovskites because they exhibit much lower bulk moduli compared to the conventional semiconductors used in photovoltaic, photocatalytic, electrocatalytic, lasing, light-emitting, detecting and other opto-electronic devices.
关键词： Electron-phonon coupling,Nonradiative recombination,All-inorganic perovskites,Time-dependent density functional theory,Defects
更新于2025-09-19 17:13:59
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Nonradiative Recombination in Perovskite Solar Cells: The Role of Interfaces
摘要： Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their VOC to values well below the Shockley–Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the VOC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome—paving the way to the thermodynamic efficiency limit.
关键词： interfacial recombination,open-circuit voltage,perovskite solar cells,photoluminescence
更新于2025-09-19 17:13:59
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Understanding the High Performance of over 15% Efficiency in Single‐Junction Bulk Heterojunction Organic Solar Cells
摘要： The highly efficient single-junction bulk-heterojunction (BHJ) PM6:Y6 system can achieve high open-circuit voltages (VOC) while maintaining exceptional fill-factor (FF) and short-circuit current (JSC) values. With a low energetic offset, the blend system is found to exhibit radiative and non-radiative recombination losses that are among the lower reported values in the literature. Recombination and extraction dynamic studies reveal that the device shows moderate non-geminate recombination coupled with exceptional extraction throughout the relevant operating conditions. Several surface and bulk characterization techniques are employed to understand the phase separation, long-range ordering, as well as donor:acceptor (D:A) inter- and intramolecular interactions at an atomic-level resolution. This is achieved using photo-conductive atomic force microscopy, grazing-incidence wide-angle X-ray scattering, and solid-state 19F magic-angle-spinning NMR spectroscopy. The synergy of multifaceted characterization and device physics is used to uncover key insights, for the first time, on the structure–property relationships of this high-performing BHJ blend. Detailed information about atomically resolved D:A interactions and packing reveals that the high performance of over 15% efficiency in this blend can be correlated to a beneficial morphology that allows high JSC and FF to be retained despite the low energetic offset.
关键词： organic photovoltaics,charge extraction,recombination,solid-state NMR,low voltage losses
更新于2025-09-19 17:13:59
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Cesium Lead Inorganic Solar Cell with Efficiency beyond 18% via Reduced Charge Recombination
摘要： Cesium-based inorganic perovskite solar cells (PSCs) are promising due to their potential for improving device stability. However, the power conversion efficiency of the inorganic PSCs is still low compared with the hybrid PSCs due to the large open-circuit voltage (VOC) loss possibly caused by charge recombination. The use of an insulated shunt-blocking layer lithium fluoride on electron transport layer SnO2 for better energy level alignment with the conduction band minimum of the CsPbI3-xBrx and also for interface defect passivation is reported. In addition, by incorporating lead chloride in CsPbI3-xBrx precursor, the perovskite film crystallinity is significantly enhanced and the charge recombination in perovksite is suppressed. As a result, optimized CsPbI3-xBrx PSCs with a band gap of 1.77 eV exhibit excellent performance with the best VOC as high as 1.25 V and an efficiency of 18.64%. Meanwhile, a high photostability with a less than 6% efficiency drop is achieved for CsPbI3-xBrx PSCs under continuous 1 sun equivalent illumination over 1000 h.
关键词： VOC loss,inorganic perovskite solar cells,recombination defects
更新于2025-09-19 17:13:59
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Detailed analysis of radiative transitions from defects in n-type monocrystalline silicon using temperature- and light intensity-dependent spectral Photoluminescence
摘要： Sub-bandgap luminescence is characteristic of radiative transitions from defects in semiconductors. However, methods to extract defect-identifying parameters from this luminescence are lacking. Here, we present a method to extract these parameters from temperature- and intensity-dependent micro-photoluminescence (μPL) spectra. The initial “coarse” analysis determines the relevant radiative recombination mechanism by fitting the integrated defect PL spectra with phenomenological models for the temperature- and intensity-dependence. The subsequent “detailed” analysis fits the integrated defect PL spectra using rigorous physical models for the defect radiative recombination and spectral line-shape. Finally, defect parameters are extracted, including the defect energy level(s). As we obtain these values directly from the defect luminescence, our method provides higher confidence than more traditional indirect methods, such as those involving band-to-band PL and photoconductance. We demonstrate our method on spatially non-uniform defects with radiative transitions in n-type monocrystalline silicon samples. It is shown that the defect PL originates from the donor-acceptor pair recombination mechanism, involving a shallow acceptor and deeper donor energy level. The acceptor level is extracted from the temperature-dependent spectra, whilst the intensity-dependent spectra give the sum of acceptor and donor energies.
关键词： Radiative transitions,Silicon,Photoluminescence,Defects,Donor-acceptor pair recombination
更新于2025-09-19 17:13:59
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Highly Stabilized Quantum Dot Ink for Efficient Infrared Light Absorbing Solar Cells
摘要： Liquid-state ligand exchange provides an efficient approach to passivate a quantum dot (QD) surface with small binding species and achieve a QD ink toward scalable QD solar cell (QDSC) production. Herein, experimental studies and theoretical simulations are combined to establish the physical principles of QD surface properties induced charge carrier recombination and collection in QDSCs. Ammonium iodide (AI) is used to thoroughly replace the native oleic acid ligand on the PbS QD surface forming a concentrated QD ink, which has high stability of more than 30 d. The ink can be directly applied for the preparation of a thick QD solid film using a single deposition step method and the QD solid film shows better characteristics compared with that of the film prepared with the traditional PbX2 (X = I or Br) post-treated QD ink. Infrared light-absorbing QDSC devices are fabricated using the PbS-AI QD ink and the devices give a higher photovoltaic performance compared with the devices fabricated with the traditional PbS-PbX2 QD ink. The improved photovoltaic performance in PbS-AI-based QDSC is attributed to diminished charge carrier recombination induced by the sub-bandgap traps in QDs. A theoretical simulation is carried out to atomically link the relationship of QDSC device function with the QD surface properties.
关键词： quantum dots,charge recombination,solar cells,theoretical simulations,ligand exchange
更新于2025-09-19 17:13:59
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Trade‐Off between Exciton Dissociation and Carrier Recombination and Dielectric Properties in Y6‐Sensitized Nonfullerene Ternary Organic Solar Cells
摘要： Organic photovoltaics (OPVs) have emerged as a promising renewable energy generation technology in past decades. However, the deep understanding of the details in exciton dissociation and carrier recombination in ternary organic solar cells (OSCs) is still lacking. Herein, a novel ternary OSC based on a PTB7-Th:Y6:ITIC blend with a power conversion efficiency (PCE) enhancement of 29% is reported. A trade-off is surprisingly found to exist between the exciton dissociation and carrier recombination process. The addition of nonfullerene acceptor Y6 in the ternary blend is found to create an efficient exciton dissociation process but accelerates the free carrier recombination process. Dielectric properties are also studied for ternary OSCs. The addition of Y6 into the binary blend is found to tune down the dielectric constant of the active layer and as a result accelerates the carrier recombination. The best performance is obtained for PTB7-Th:Y6(5 wt%):ITIC(95 wt%)-based ternary devices. In addition to its balanced charge carrier mobility and efficient charge extraction process, PTB7-Th:Y6(5 wt%):ITIC(95 wt%)-based ternary devices reach a balance in the trade-off between the exciton dissociation and carrier recombination process and thus achieve the highest short-circuit current density (Jsc) value.
关键词： nonfullerene,carrier recombination and dielectric constants,ternary,organic solar cells,exciton dissociation
更新于2025-09-19 17:13:59
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Practical target values of Shockleya??Reada??Hall recombination rates in statea??ofa??thea??art triplea??junction solar cells for realizing conversion efficiencies within 1% of the internal radiative limit
摘要： In order to identify the cause of the difference between actual efficiency and the theoretical limit in state-of-the-art triple-junction solar cells, we investigate the internal luminescence efficiency in the depletion region (ηdep int ). The average internal luminescence efficiency of the whole subcell volume ( (cid:1)η int) is obtained experimentally, and the ηdep int is deduced by numerical calculations using rate equations. We find that (cid:1)η int and ηdep int agree well in the low-recombination current regime including the maximum power point. This indicates that the non-radiative recombination loss at the maximum power point strongly depends on the recombination in the depletion region. Furthermore, we determine the actual Shockley–Read–Hall recombination coefficient in the depletion region, Adep, which is proportional to the effective density of recombination centers. Our analysis reveals the target values of Adep required for realizing conversion efficiencies that are within 1% of the internal radiative limit. The analysis also clarifies the extent of reduction of the effective density of recombination centers (in the depletion region) that is required to realize a given target efficiency.
关键词： recombination center,AB model,III–V compound solar cell,internal luminescence efficiency
更新于2025-09-19 17:13:59
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Insights into the role of interface modification in performance enhancement of ZnTe:Cu contacted CdTe thin film solar cells
摘要： CdTe has become a leading contributor in the thin-film photovoltaic market. A suitable back contact is still one of the most crucial issues to realize efficient CdTe thin film solar cells. Herein, we intensively studied the mechanisms of interfacial modification and device performance enhancement for the representative ZnTe:Cu back contact structure. It’s found that, in spite the as-deposited ZnTe:Cu buffer could reduce the contact barrier, the device performance is still limited by the increased defect-related recombination. A controlled heat treatment process is proved to be effective in alleviating the recombination loss at the back contact. Detailed characterizations demonstrate that the CdTe/ZnTe:Cu interface reaction happens and the interfacial composition is modified during the heat treatment process, which optimize the interfacial chemical states and band alignment. The improved interfacial properties decrease the defect-related recombination and promote the holes transport, and consequently improve the device efficiency greatly.
关键词： ZnTe:Cu,Recombination,CdTe,Solar cell,Interface modification
更新于2025-09-19 17:13:59