- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Asymmetric 9,9a?2-bifluorenylidene-based small molecules as the non-fullerene acceptors for organic photovoltaic cells
摘要： Three new asymmetric 9,9'-bifluorenylidene-based derivatives, 2,7-dibutoxyl-3',6'-bis(5-methylenemalononitrile-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TDCN2), 2,7-dibutoxyl-3',6'-bis(5-(methylene-indene-1,3-dione)-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TID2) and 2,7-dibutoxyl-3',6'-bis(5-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile)-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TDCI2), were successfully synthesized by grafting different electron-withdrawing groups (malononitrile (DCN), 1H-indene-1,3(2H)-dione (ID) and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (DCI)), which were used as the electron acceptors for organic photovoltaic cells. By changing the electron-withdrawing ability of the terminal group, the molecular energy level and band gap can be easily adjusted. The optical bandgaps of the three compounds in the thin films decreased with increasing the electron-withdrawing ability of the terminal group. Besides, the lateral chains of alkoxy groups located at the asymmetric end also play a certain influence on the solubility, molecular aggregation and the miscibility with polymer donor. Among these electron acceptors, the photovoltaic cell fabricated PBDB-T:BF-TDCI2 exhibited a maximum power conversion efficiency of 4.85% with an open-circuit voltage of 0.88 V and a low energy loss of 0.62 eV. By investigating different processing processes, the results showed that the power conversion efficiency can be improved by 20% with simple solvent annealing treatment. Through further study on the morphology and photophysical properties of the active layers, it was found that the processed device had better phase separation size and morphology, which was favorable to enhancing the intermolecular interaction, thus improving exciton separation and charge transfer in the active layer.
关键词： Non-fullerene acceptor,Organic photovoltaic cell,9,9'-bifluorenylidene derivative,Asymmetric molecule
更新于2025-09-19 17:13:59
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Small molecule donor based on alkoxylated benzothiadiazole unit: Synthesis and photovoltaics properties
摘要： Two small molecule donors (namely BTRO and BTCN) based on the benzothiadiazole unit were synthesized in this study. In comparison to BTRO, BTCN has a narrower absorption spectrum, however, BTCN has better crystallinity, higher carrier mobility, and better light absorption that is complementary to IDIC-4F. Non-fullerene all small molecule organic solar cells (SM-OSCs) based on BTCN: IDIC-4F exhibited a power conversion efficiency (PCE) of 4.62% with short circuit current density (Jsc) of 11.46 mA/cm2, open-circuit voltage (Voc) of 0.89 V, and fill factor (FF) of 0.45. In contrast, non-fullerene SM-OSCs based on BTRO: IDIC-4F showed PCE, Jsc, Voc, and FF values of 4.08%, 11.04 mA/cm2, 0.91 V, and 0.41, respectively. Our results show that benzothiadiazole is a very good acceptor unit for regulating the absorption and energy levels of non-fullerene SM-OSCs.
关键词： benzothiadiazole,all small molecule organic solar cells,non-fullerene,small molecule donor
更新于2025-09-19 17:13:59
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Designing alkoxy-induced based high performance near infrared sensitive small molecule acceptors for organic solar cells
摘要： Scientist are dedicated to design and synthesize efficient photovoltaic materials to overcome the energy crises. In this regard, herein, we have designed four new small acceptor molecules namely (A1, A2, A3 and A4) for better performance in organic solar cells. These molecules consist Alkoxy-Induced Naphtho-dithiophene core unit flanked with 2,2-ethylidene-5,6-dicyano-3-oxo-2,3-dihydroinden-1-ylidene-malononitrile (A1), methyl-2-cyano-2,2-ethylidene-5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene-acetate (A2), 5,2-ethylidene-5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene-3-methyl-2-thioxothiazolidin-4-one (A3) and 2,5-ethylidene-6-oxo-5,6-dihydrocyclopenta-thiophen-4-ylidene-malononitrile (A4) end-capped acceptor groups. Their optical, electrical and geometries have been compared with reported molecule R. Frontier molecular orbital diagram reveal excellent charge transfer rate, The electron density is shifted from donor to acceptor unit. Among all, A1 exhibits the highest absorption in the visible region (λmax) at 798 nm in chloroform solvent. The maximum open circuit voltage (2.08 V) is observed for A3 when blended with PTB7-Th donor polymer. All studied molecules have high charge mobilities due to lower reorganization energy values with respect to model molecule R. A1 has the highest electron mobility among all molecules due to lower value of reorganization energy which is 0.0034. Furthermore, all designed molecules show good Solubilities in organic solvent. A2 exhibit high value of dipole moment which reveal good solubilities in fabrication process.
关键词： Transition density matrix,Non-fullerene acceptor,Open circuit voltages,Naphtho-dithiophene,Reorganization energy,Fused ring electron acceptor
更新于2025-09-19 17:13:59
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Impact of intentional photo-oxidation of a donor polymer and PC <sub/>70</sub> BM on solar cell performance
摘要： Impact of intentional photo-oxidation of a donor polymer and PC70BM on solar cell performance. A short lifetime is the main factor hindering the wider implementation of low-cost organic photovoltaics through non-ideal encapsulation layers is a known cause of degradation for polymer/fullerene based solar cells. To better understand the origin of this performance degradation, we study the effect of intentional exposure of the photo-active layer to simulated sunlight (AM1.5) in air both on the solar cell performance and on the molecular semiconductor materials. Cathode-free thin films of a blend of the electron donor polymer poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and the electron acceptor fullerene derivative [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) were exposed to simulated sunlight in air. Fourier-transform infrared spectra demonstrate the formation of carbonyl photo-oxidation products in the blend films, as well as in the pristine polymer and fullerene films. Solar cells prepared with photo-oxidized active layers show increasingly degraded electrical performance (lower short circuit current, open circuit voltage and fill factor) with increasing exposure time. The increased diode ideality factor indicates that trap-assisted recombination hinders device operation after exposure. The external quantum efficiency decreases drastically with increasing exposure time over the whole photon energy range, while the UV-vis absorption spectra of the blend films only show a mild photo-induced bleaching. This demonstrates that not only the photo-induced degradation of the solar cell performance is not predominantly caused by the loss in light absorption, but charge transport and collection are also hampered. This is explained by the fact that photo-oxidation of PC70BM causes bonds in its conjugated cage to break, as evidenced by the decreased p* intensity in C1s-NEXAFS spectra of PC70BM films. This degradation of unoccupied states of PC70BM will hinder the transport of photo-generated electrons to the electrode. Surface photovoltage spectroscopy gives direct evidence for gap states at the surface of a PC70BM film, formed after 2 hours of exposure and resulting in upward band bending at the PC70BM/air surface. These observations indicate that the photo-oxidation of PC70BM is likely to be the main cause of the performance degradation observed when the photoactive layer of a TQ1:PC70BM solar cell is intentionally exposed to light in air.
关键词： polymer/fullerene solar cells,photo-oxidation,organic photovoltaics,PC70BM,degradation,trap-assisted recombination,charge transport,TQ1
更新于2025-09-19 17:13:59
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High-Efficiency Nonfullerene Organic Solar Cells Enabled by 1000 nm Thick Active Layers with a Low Trap-State Density
摘要： The high-efficient organic solar cells (OSCs) with thicker active layers are potential candidates for large-area solar panels fabrication. The low charge carrier mobility of the photoactive materials has been identified as the major problem hindering photovoltaic performance of the thick-film OSCs. In this study, high performance of ultra-thick film organic solar cells employing a non-fullerene acceptor BTP-4Cl and a polymer donor PBDB-TF is demonstrated. Two blends (PBDB-TF:BTP-4Cl and PBDB-TF:IT-4F) show comparable mobilities and excellent photovoltaic characteristics in thin-film devices; while in the 1000-nm-thick devices, although they both exhibit desirable and balanced mobilities, the PBDB-TF:BTP-4Cl-based blend possesses lower trap-state density than the IT-4F-based counterpart, leading to lower trap-assist recombination, longer carrier lifetime, and thus a much higher short circuit current density in the device. As a result, the BTP-4Cl-based 1000-nm-thick OSC achieves a remarkable PCE of 12.1%, which greatly outperforms the IT-4F-based devices (4.72%). What is more, for a 1000-nm thick device with active area of 4 cm2, a promising efficiency of 10.1% was obtained, showing its great potential in future large-scale production.
关键词： trap-state density,ultra-thick active layers,high efficiency,non-fullerene organic solar cells,charge carrier mobility
更新于2025-09-19 17:13:59
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Solar-Powered Artificial Photosynthesis Coupled with Organic Synthesis
摘要： Organic photovoltaics (OPVs) have attracted much attention because of the advantages in low-cost and large-area fabrication and the great potentials in achieving flexible and semi-transparent devices. However, compared with inorganic and perovskite solar cells, OPVs show relatively low photoelectric conversion efficiencies, which is admittedly attributed to intrinsically low dielectric constants of organic materials resulting in large energy losses. With the rapid development of fused-ring electron acceptors especially with an acceptor (A)-donor (D)-acceptor (A) arrangement, PCEs of OPV devices quickly surpassed 12% and even reached 16% in a very short period, in quite a few of which the Elosss are less than 0.6 eV. Although it is common for inorganic or perovskite solar cells, high-performance OPVs with the Elosss less than 0.5 eV are quite rare up to date, which means that the Eloss is still the key factor that limits the photovoltaic efficiency of the OPV technique. Nonetheless, progresses in the development of efficient OPVs by reducing the Eloss to less than 0.5 eV have been made in the past few years.
关键词： Photovoltaic efficiency,Energy loss,Organic solar cells,Non-fullerene acceptors
更新于2025-09-19 17:13:59
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On the absence of triplet exciton loss pathways in non-fullerene acceptor based organic solar cells
摘要： We investigate the viability of highly efficient organic solar cells (OSCs) based on non-fullerene acceptors (NFA) by taking into consideration efficiency loss channels and stability issues caused by triplet excitons (TE) formation. OSCs based on a blend of the conjugated donor polymer PBDB-T and ITIC as acceptor were fabricated and investigated with electrical, optical and spin-sensitive methods. The spin-Hamiltonian parameters of molecular TEs and charge transfer TEs in ITIC e.g., zero-field splitting and charge distribution, were calculated by Density Functional Theory (DFT) modelling. In addition, the energetic model describing the photophysical processes in the donor-acceptor blend was derived. Spin-sensitive photoluminescence measurements prove the formation of charge transfer (CT) states in the blend and the formation of TEs in the pure materials and the blend. However, no molecular TE signal is observed in the completed devices under working conditions by spin-sensitive electrical measurements. The absence of a molecular triplet state population allows to eliminate a charge carrier loss channel and irreversible photooxidation facilitated by long-lived triplet states. These results correlate well with the high power conversion efficiency of the PBDB-T:ITIC-based OSCs and their high stability.
关键词： triplet excitons,Density Functional Theory,organic solar cells,non-fullerene acceptors,photoluminescence detected magnetic resonance,electrically detected magnetic resonance
更新于2025-09-19 17:13:59
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Achieving Optimal Bulk Heterojunction in All-Polymer Solar Cells by Sequential Processing with Nonorthogonal Solvents
摘要： Developing efficient all-polymer solar cells (all-PSCs) has always been a long-standing challenge due to the unfavorable morphology caused by conventional blend-casting (BC). Here we first employ the methodology of sequential processing (SP) with nonorthogonal solvents to fabricate facilely all-PSCs. A highly crystalline polymer donor PBDB-T is used to construct a well-organized underlying film, while a new polymer FPDI-BT1 is selected as the acceptor to be intercalated into the amorphous or semicrystalline regions of PBDB-T during the secondary deposition. By tuning the solvent composition for FPDI-BT1 processing, a bulk heterojunction-like configuration, rather than a traditional bilayer device, is obtained facilely without the need of further processing treatment. The extremely boosted power conversion efficiency of 7.15% from SP device is achieved, which is more than twice as efficient as the BC analogue (3.57%). The results demonstrate that SP is a promising strategy to fabricate high-performance all-PSCs with tunable configurations of active layers.
关键词： perylene diimide,non-fullerene acceptor,sequential processing,all-polymer solar cells,morphological control
更新于2025-09-19 17:13:59
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Improving Performance of Non-fullerene Organic Solar Cells over 13% by Employing Silver Nanowires Doped PEDOT:PSS Composite Interface
摘要： Ag NWs/PEDOT:PSS composite was prepared by a facile solution-processing method, and was employed as anode interface in non-fullerene organic solar cells (OSCs). With the presence of Ag NWs (5%, v/v%)/PEDOT:PSS interfacial layer, a high power conversion efficiency (PCE) up to 13.53% was achieved based on PBDB-T-2Cl:IT-4F photoactive layer system, much higher than the efficiency of the controlled counterpart device with pristine PEDOT:PSS as anode modifier. Simultaneous enhancements in short-circuit current and fill factor were observed, in comparison to the case of pristine PEDOT:PSS interface, due to the improved electrical conductivity of Ag NWs/PEDOT:PSS composites accompanied by the increased work function for a better matching with ITO counter electrode, which facilitated the increased charge transmission, and the reduced charge recombination at the anode/photoactive interface for the improved device performance. The results clearly revealed that Ag NWs/PEDOT:PSS composite interface is beneficial to improve the charge extraction and in favor of realizing highly efficient non-fullerene OSCs.
关键词： composite interface,electrical conductivity,Ag nanowires,recombination,Non-fullerene organic solar cells
更新于2025-09-19 17:13:59
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Interfacial Bridge Using a <i>cis</i> ‐Fulleropyrrolidine for Efficient Planar Perovskite Solar Cells with Enhanced Stability
摘要： Fullerene derivatives, especially after purposely functionalization, have potential to efficiently passivate interfacial defects between perovskites and electron transport layers. In this work, a fullerene derivative with amine functional group, 2,5-diphenyl C60 fulleropyrrolidine (DPC60), is synthesized and employed as an interfacial layer between a perovskite and SnO2 in planar perovskite solar cells (PSCs). The cis-configuration and the specific amine group of DPC60 effectively enhance the chemical interaction between the perovskite and DPC60, promoting the passivation of perovskite defects at the interface. The suitable energy level of DPC60 and the improved conductivity of the SnO2/DPC60 film facilitate the electron extraction from the perovskite layer. As a result, PSCs incorporated with DPC60 reach a PCE of 20.4% with high reproducibility, which is much higher than that of the bare SnO2 based devices (18.8%). Furthermore, the hydrophobic DPC60 layer suppresses heterogeneous nucleation and improves the crystallinity of the perovskite film, resulting in better device stability, retaining 82% of its initial efficiency after 200 h of 1 sun continuous irradiation and thermal ageing (55 ± 5 °C).
关键词： fullerene derivatives,chemical interactions,perovskite solar cells,passivation,energy level alignment
更新于2025-09-19 17:13:59