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Sandwich-like electron transporting layer to achieve highly efficient perovskite solar cells
摘要： Passivating the carrier recombination at the heterojunction interface and improving the efficiency of charge separation are effective means to boost the performance of perovskite solar cells (PSCs). The interface modification between the anode and the electron transporting layer (ETL) or constructing bilayer structural ETLs has been proved to be the effective way to achieve high-efficient charge extraction and collection. Combining the advantages of both techniques might further achieve lower energy loss and higher efficiency in PSCs. Herein, we design a sandwich-like SnO2-CQDs-SnO2 (S–C–S) ETLs, i.e. an ultrathin band-gap tunable carbon quantum dots (CQDs) layer is inserted between ultrathin SnO2 bottom layer and SnO2 top layer. The bottom ultrathin SnO2 layer passivates the defects of SnO2:F (FTO) and reduces the carrier recombination at the FTO/ETLs interface. The CQDs layer enhances the optical transmission of ETLs, accelerates carrier transport process and improves the hole-blocking ability. Such S–C–S ETLs greatly enhance the power conversion efficiency (PCE) of PSCs and eliminate hysteresis to the maximum extent. This work provides a new concept for designing novel electronic transmission materials for solar cells, and lays the foundation for further achieving higher PCE in PSCs.
关键词： Power conversion efficiency,Sandwich-like electron transporting layer,Band alignment,Perovskite solar cell,Interface modification
更新于2025-09-19 17:13:59
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Numerical modeling of lead-free perovskite solar cell using inorganic charge transport materials
摘要： Ten years after their first mention in report on solar cell implementation, organic-inorganic hybrid perovskites are still the focal point of photovoltaic research. Proper selection of material for different layers has enabled high power conversion efficiency (PCE) values that presently surpass 24%. Unfortunately, the metal halide perovskite solar cells (PSC) contain toxic lead, which is a serious concern for their commercialization process. To tackle lead toxicity issues in perovskite-based solar cells, intensive research by PSC research fraternity is ongoing to develop lead-free metal halide perovskite. In this paper, a novel solar cell configuration which consists of FTO/Transition Metal Di-Chalcogenides/Perovskite/Copper thiocyanate/Au is proposed. In this Transition Metal Di-Chalcogenides (Tungsten Disulfide) is used as an electron transport metal (ETM) due to its high electron mobility and Copper thiocyanate (CuSCN) is used as a hole transport metal (HTM) due to its high transparency and ideal band alignment with perovskite. Impact of variation in thickness of perovskite layer, electron transport layer and hole transport layer on performance parameters were examined. A PCE of 19.84% is achieved at the optimal perovskite layer thickness of 700 nm. When the thickness surpasses 700 nm, PCE drops due to an increase in the recombination of electron-hole pairs. Impact of interfacial defects on the performance parameter was also scrutinized. Simulation results reveal that the interfacial defect of ETM/Perovskite has a larger impact on performance parameters than that of Perovskite/HTM defect when light is irradiated from the ETM side. We also investigated the effect of temperature variation on device performance. The PSC showed optimum performance in the range of 20 °C to 50 °C and the ideal working temperature was viewed as 30 °C.
关键词： Transition metal di-chalcogenides,Power conversion efficiency,Stability,Lead-free perovskite,Copper thiocyanate
更新于2025-09-19 17:13:59
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D-A Copolymer Donor Based on Bithienyl Benzodithiophene D-unit and Monoalkoxy Bifluoroquinoxaline A-unit for High Performance Polymer Solar Cells
摘要： Molecular frontier orbital energy level and aggregation behavior regulation of polymer donors are feasible way to improve the photovoltaic performance of polymer solar cells (PSCs). Here, we design and synthesize a new D-A copolymer donor PBQ10 based on bithienyl benzodithiophene D-unit and monoalkoxy-substituted bifluoroquinoxaline A-unit, which shows obviously down-shifted highest occupied molecular orbital energy level in comparison with the control polymer PBQ7 with dialkoxyphenyl substituent on the bifluoroquinoxaline A-unit. Moreover, PBQ10 exhibits more preferential face-on molecular orientation and tighter π–π stacking in the vertical direction of substrate than that of PBQ7, which significantly improves the hole mobility of PBQ10 to 5.22×10-4 cm2 V-1 s-1 in comparison with that (1.71×10-4 cm2 V-1 s-1) of PBQ7. As a result, the PBQ10-based PSC with Y6 as acceptor demonstrates an impressive power conversion efficiency (PCE) of 16.34 % with simultaneously increased open circuit voltage and fill factor, which is significantly increased than the PBQ7-based PSC with PCE of 13.45 %, and is one of the highest PCEs in binary PSCs. The result suggests that rational side chain optimization of polymer donor is an efficient way to regulate molecular energy level and self-assembly feature, thus to improve the PCE of PSCs.
关键词： Power conversion efficiency,Polymer solar cells,Bithienyl benzodithiophene,Monoalkoxy-substituted bifluoroquinoxaline,D-A copolymer donor
更新于2025-09-19 17:13:59
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13.2% Efficiency of Organic Solar Cells by Controlling Interfacial Resistance resulted from Well-distributed Vertical Phase Separation
摘要： Two strategies were investigated to improve the efficiency of organic solar cells (OSCs) with the aim of controlling the interfacial resistance in the devices: the use of a ternary active layer and the introduction of conjugated polymers. The ternary active layer was formed by introducing PC71BM between a high-performance non-fullerene photoactive material P(Cl-Cl)(BDD=0.2) and the IT-4F-based binary active layer, thereby reducing the interfacial resistance between the donor and acceptor via vertical phase separation. Furthermore, the introduction of the conjugated polymer PFN-Br created a well-dispersed separation attributable to enhancement of the interfacial contact with the active layer, and simultaneous reduction of the interfacial resistance. Consequently, the synergetic effect of the ternary active layer and PFN-Br enhanced the short-circuit current density (JSC) and fill factor (FF) to realize power conversion efficiency (PCE) of 13.2%.
关键词： Power conversion efficiency,Interfacial resistance,Conjugated polymers,Ternary active layer,Organic solar cells
更新于2025-09-19 17:13:59
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Small-molecular Iridium complex based organic solar cells with improved photovoltaic performance through device optimization
摘要： Small-molecular Iridium complex based organic solar cells (OSCs) show inferior power conversion efficiencies (PCEs) to pure organic/polymer analogues. To further improve the performance of such OSCs, we reported a bilayer device structure, which was fabricated by sequentially spin-coating a p-type polymer semiconductor (poly[4,4’-bis(2-butyloctoxycarbonyl-[2,2’-bithiophene]-5,5-diyl)-alt-(2,2’bithiophene-5,5’diyl)]) (PDCBT) layer and a bulk-heterojunction (BHJ) layer with cyclometalated Ir complex (TBzIr) as donor and PC71BM as acceptor. Compared to the original TBzIr:PC71BM BHJ device, the bilayer PDCBT/ TBzIr:PC71BM structure exhibited identical high open circuit voltages of 0.92 V, both increased short circuit current from 9.25 to 11.14 mA cm-2 and fill factor from 0.46 to 0.61. The p-type PDCBT layer is inserted to afford extra light absorption, assist the upper BHJ blends to form optimized morphologies, as well as provide supplementary donor-acceptor interfaces to facilitate exciton dissociation. Therefore, the PCE could be significantly improved from 3.91% for TBzIr:PC71BM to 6.17% for PDCBT/TBzIr:PC71BM. To our best knowledge, this is the highest efficiency ever reported for small-molecular Ir complex based organic solar cells.
关键词： bilayer device structure,power conversion efficiency,organic solar cells,small-molecular,Iridium complex
更新于2025-09-19 17:13:59
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Device physics of back-contact perovskite solar cells
摘要： Back-contact perovskite solar cells (PSCs) are a promising candidate to further increase power conversion efficiency (PCE) and have been the subject of many investigations. However their full potential has not been achieved due a lack of a complete understanding of their operation from a device physics perspective. In this study, a detailed photoelectrical model for back-contact PSCs is developed by coupling a drift-diffusion description of free charge transport model with ion migration currents and emitted-carrier generation resulting from photon recycling. By studying the influence of relevant electrical parameters, the interplay between charge generation, transport and recombination, is revealed to further clarify the design principles based on devices with a back-contact structure. Although devices featuring the back-contact structure exhibit a sensitivity to electrical parameters, a high PCE exceeding 25% is predicted if the interface passivation and perovskite film quality can be well controlled. Different conduction band and valence band offsets offer various screening opportunities for functional materials with high efficiencies are introduced. Additionally, the simulated results revealed that mobile ions degrade the device performance if the average ion concentration exceeds 1016 cm?3. Furthermore, we point out that photon recycling can effectively compensate against radiative recombination, thereby resulting in an improved open circuit voltages. The results provide a new understanding of the carrier transport dynamics, ion migration, and photon recycling effects for the back-contact structure, which can be applied to a systematic improvement in the design of high efficiency PSCs.
关键词： Power conversion efficiency,Ion migration,Back-contact perovskite solar cells,Photoelectrical model,Photon recycling
更新于2025-09-19 17:13:59
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Achieving Organic Solar Cells with efficiency over 14% based on a non-Fullerene Acceptor incorporating the Cyclopentathiophene unit Fused backbone
摘要： The cyclopentadithiophene (CPT) unit is a classic building block for constructing organic semiconductor materials with excellent performances. In this work, we designed and synthesized a new acceptor BCPT-4F, incorporating a CPT fused central backbone. BCPT-4F shows a redshift absorption in near-infrared region compared with CPT based acceptors with unfused backbone. Importantly, the photovoltaic device based on PBDB-T:BCPT-4F gave a promising power conversion efficiency (PCE) of 12.43% with a high short circuit current density of 22.96 mA cm?2. Furtherly,based on the above binary device, the ternary device with F-Br as the third component achieved a high PCE of 14.23%, which is presently the highest efficiency for devices with CPT based photovoltaic materials.
关键词： power conversion efficiency,non-fullerene acceptor,ternary device,cyclopentadithiophene,organic photovoltaics
更新于2025-09-19 17:13:59
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Secondary Bonds Modifying Conjugatea??Blocked Linkages of Biomassa??Derived Lignin to Form Electron Transfer 3D Networks for Efficiency Exceeding 16% Nonfullerene Organic Solar Cells
摘要： Fabricating high-efficient electron transporting interfacial layers (ETLs) with isotropic features is highly desired for all-directional electron transfer/collection from an anisotropic active layer, achieving excellent power conversion efficiency (PCEs) on nonfullerene acceptor (NFA) organic solar cells (OSCs). The complicated synthesis and cost-consumption in exploring versatile materials arouse great interest in the development of binary-doping interlayers without phase separation and flexible manipulation. Herein, for the first time, a novel cathode interfacial layer based on biomass-derived demethylated kraft lignin (DMeKL) is proposed. Features of multiple phenolic-hydroxyl (PhOH) and uniform-distributed render DMeKL to exhibit an excellent bonding capacity with amino terminal substituted perylene diiminde (PDIN), and successfully form a high-efficient isotropic electron transfer 3D network. Synchronously, secondary bonds completely modify conjugate-blocked linkages of DMeKL, significantly enhance the electron transporting performance on cross-section and vertical-sections, and repair the contact of PDIN with active layer. The DMeKL/PDIN-based 3D-network exhibits well-matched work function (WF) (–4.34 eV) with cathode (–4.30 eV) and energy level of electron acceptor (–4.11 eV). DMeKL/PDIN-based NFAs-OSC shows excellent short-circuit current density (26.61 mA cm–2) and PCE (16.02%) beyond the classic PDIN-based NFA-OSC (25.64 mA cm–2, 15.41%), which is the highest PCEs among biomaterials interlayers. The results supply a novel method to achieve high-efficient cathode interlayer for NFAs-OSCs.
关键词： secondary bonds,nonfullerene acceptor organic solar cells,electron transfer 3D network,biomass-derived lignin,power conversion efficiency
更新于2025-09-19 17:13:59
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Non-fullerene acceptor fibrils enable efficient ternary organic solar cells with 16.6% efficiency
摘要： Optimizing the components and morphology within the photoactive layer of organic solar cells (OSCs) can significantly enhance their power conversion efficiency (PCE). A new A-D-A type non-fullerene acceptor IDMIC-4F is designed and synthesized in this work, and is employed as the third component to prepare high performance ternary solar cells. IDMIC-4F can form fibrils after solution casting, and the presence of this fibrillar structure in the PBDB-T-2F:BTP-4F host confines the growth of donors and acceptors into fine domains, as well as acting as transport channels to enhance electron mobility. Single junction ternary devices incorporating 10 wt% IDMIC-4F exhibit enhanced light absorption and balanced carrier mobility, and achieve a maximum PCE of 16.6% compared to 15.7% for the binary device, which is a remarkable efficiency for OSCs reported in literature. This non-fullerene acceptor fibril network strategy is a promising method to improve the photovoltaic performance of ternary OSCs.
关键词： ternary solar cells,non-fullerene acceptor fibrils,power conversion efficiency
更新于2025-09-19 17:13:59
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A universal strategy combining interface and grain boundary engineering for negligible hysteresis and high efficiency (21.41%) planar perovskite solar cells
摘要： Planar perovskite solar cells (PSCs) release the potential to compete with mesoporous PSCs because of comparable power conversion efficiency (PCE) and compatible with the preparation of flexible or tandem PSCs. However, the severe current-voltage hysteresis occurring in PSCs is still a big issue, attributable to the trap-induced charge recombination and ion migration. Herein, we develop a universal strategy combining interface (PMMA:C60) and grain boundary (PTABr) engineeing to effectively eliminate hysteresis of planar PSCs by finely tuning the electron transport layer/perovskite interface and perovskite film morphology (grain size and grain boundary). Microstructure and spectra characterizations, density functional theory (DFT) calculations and photoelectric measurements reveal that this ingenious combination of the two engineering approaches effectively reduce the trap sites and enlarge perovskite grain size, hence leading to negligible hysteresis and high performance PSCs based on various compositional perovskites including MAPbI3, Cs0.15FA0.85PbI3 and Cs0.15FA0.75MA0.1PbI3, with PCE of 18.99%, 19.82%, 21.41% and extra-low hysteresis index of 0.011, 0.007, 0.005, respectively. This work demonstrates a universal strategy to fabricate high efficiency and negligible hysteresis PSCs regardless of perovskite composition.
关键词： hysteresis,power conversion efficiency,grain boundary engineering,interface engineering,perovskite solar cells
更新于2025-09-19 17:13:59