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Thienyl Sidechain Substitution and Backbone Fluorination of Benzodithiophene-Based Donor Polymers Concertedly Minimize Carrier Losses in ITIC-Based Organic Solar Cells
摘要： Non-fullerene acceptor (NFA) based organic solar cells have outperformed fullerene-based devices, yet their photophysics is less well understood. Herein, changes in the donor polymer backbone side-chain substitution and backbone fluorination in benzodithiophene (BDT)-thiophene copolymers are linked to the photophysical processes and performance of bulk heterojunction (BHJ) solar cells, using ITIC as NFA. Increased geminate recombination is observed when the donor polymer is alkoxy-substituted in conjunction with faster non-geminate recombination of free charges, limiting both the short circuit current and device fill factor. In contrast, thienyl-substitution reduces geminate recombination, albeit non-geminate recombination remains significant, leading to improved short circuit current density, yet not fill factor. Only the combination of thienyl-substitution and polymer backbone fluorination yields both efficient charge separation and significantly reduced non-geminate recombination, resulting in fill factors (FFs) in excess of 60 %. Time-delayed collection field measurements ascertain that charge generation is field-independent in the thienyl-substituted donor polymer:ITIC systems, while weakly field dependent in the alkoxy-substitued polymer:ITIC blend, indicating the low FFs are primarily caused by non-geminate recombination. This work provides insight into the interplay of donor polymer structure, BHJ photophysics, and device performance for a prototypical NFA, namely ITIC. More specifically, it links the donor polymer chemical structure to quantifiable changes of kinetic parameters and the yield of individual processes in ITIC-based BHJ blends.
关键词： non-fullerene acceptor,ultrafast spectroscopy,bulk heterojunction,charge generation,organic photovoltaics
更新于2025-09-23 15:19:57
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A Trifluoromethyl Group Modified Non-fullerene Acceptor Towards Improved Power Conversion Efficiency Over 13% in Polymer Solar Cells
摘要： Herein, we report a new molecule structure modification strategy for non-fullerene small molecule electron acceptors (NFAs) for solar cells through trifluoromethylation of end-capping groups. The synthesized trifluoromethylated acceptor ITCF3 exhibits narrower band gap, stronger light absorption, lower molecular energy levels and better electron transport property comparing to the reference NFA without trifluoromethyl group (ITIC). Bulk heterojunction solar cells based on ITCF3 combined with PM6 polymer donor exhibit a significantly improved power conversion efficiency of 13.3% comparing with ITIC-based device (8.4%). This work reveals great potential of trifluoromethylation in design of efficient photovoltaic acceptor materials.
关键词： power conversion efficiency,non-fullerene acceptor,trifluoromethyl group,organic solar cell,polymer
更新于2025-09-23 15:19:57
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With PBDB-T as the Donor, the PCE of Non-Fullerene Organic Solar Cells Based on Small Molecule INTIC Increased by 52.4%
摘要： At present, most high-performance non-fullerene materials are centered on fused rings. With the increase in the number of fused rings, production costs and production difficulties increase. Compared with other non-fullerenes, small molecule INTIC has the advantages of easy synthesis and strong and wide infrared absorption. According to our previous report, the maximum power conversion efficiency (PCE) of an organic solar cell using PTB7-Th:INTIC as the active layer was 7.27%. In this work, other polymers, PTB7, PBDB-T and PBDB-T-2F, as the donor materials, with INTIC as the acceptor, are selected to fabricate cells with the same structure to optimize their photovoltaic performance. The experimental results show that the optimal PCE of PBDB-T:INTIC based organic solar cells is 11.08%, which, thanks to the open voltage (VOC) increases from 0.80 V to 0.84 V, the short circuit current (JSC) increases from 15.32 mA/cm2 to 19.42 mA/cm2 and the fill factor (FF) increases from 60.08% to 67.89%, then a 52.4% improvement in PCE is the result, compared with the devices based on PTB7-Th:INTIC. This is because the PBDB-T:INTIC system has better carrier dissociation and extraction, carrier transportation and higher carrier mobility.
关键词： polymer solar cells (PSCs),synthesize easily,carrier transportation and extraction,carrier mobility,strong and wide infrared absorption,non-fullerene small molecule acceptor
更新于2025-09-23 15:19:57
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Highly efficient ternary polymer solar cell with two non-fullerene acceptors
摘要： Polymer solar cells (PSCs) based on binary and ternary active layers were built using PBDB-T polymer as donor and two non-fullerene acceptors (MPU2 and MPU3) with different DPP cores and terminal units but different conjugation length. The studied binary PSCs showed PCE (power conversion efficiency) values of 8.22% (PBDB-T:MPU2) and 9.77% (PBDB-T:MPU3). The VOC measured using the MPU3-based acceptor was higher than that obtained using MPU2 – this difference is attributed to a higher LUMO energy level of MPU3. MPU2 and MPU3 present complementary absorptions in the wavelength range where PBDB-T exhibits a poor absorption, thus the combination of these materials offers great potential for the fabrication of ternary PSCs. The solar cell with an optimized ternary layer PBDB-T:MPU2:MPU3 (1:1:1) showed an PCE value of 10.78%, higher than those obtained for the binary devices due to the enhanced of JSC and FF values. And, since the emission of MPU3 partially overlaps with the absorption of MPU2, the transfer of energy from MPU3 to MPU2 can improve the exciton utilization efficiency and achieve enhanced overall power conversion efficiency in this ternary solar cell.
关键词： Polymer donor,Power conversion efficiency,Non-fullerene acceptor,Ternary polymer solar cells
更新于2025-09-23 15:19:57
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High-Performance Ternary Organic Solar Cells with Controllable Morphology via Sequential Layer-by-Layer Deposition
摘要： Ternary blending of light harvesting materials has been proven to be a potential strategy to improve the efficiency of solution processed organic solar cells (OSCs). However, the optimization of ternary system is usually more complicated than the binary one as the morphology of conventional ternary blend films is very difficult to control, thus undermining the potential of ternary OSCs. Herein, we report a general strategy for better control of the morphology of ternary blend films composed of a polymer donor and two non-fullerene small molecule acceptors for high-performance OSCs using sequential layer-by-layer (LbL) deposition method. The resulted LbL films form bicontinuous interpenetrating network structure with high crystallinity of both the donor and acceptor materials, showing efficient charge generation, transport and collection properties. In addition, the power conversion efficiencies (PCEs) of the ternary LbL OSCs are less sensitive to the blending ratio of the third component acceptor, providing more room to optimize the device performance. As a result, optimal PCEs of over 11%, 13 % and 16 % were achieved for the LbL OSCs composed of PffBT4T-2OD/IEICO-4F:FBR, PBDB-T-SF/IT-4F:FBR and PM6/Y6:FBR, respectively. Our work provides useful and general guidelines for the development of more efficient ternary OSCs with better controlled morphology.
关键词： sequential layer-by-layer deposition,non-fullerene acceptor,ternary organic solar cell,high performance,morphology control
更新于2025-09-23 15:19:57
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Performance enhancement of conjugated polymer-small molecule-non fullerene ternary organic solar cells by tuning recombination kinetics and molecular ordering
摘要： We present our study of conjugated polymer-small molecule (SM)-non-fullerene ternary organic solar cells (OSCs), which employs conjugated polymer PTB7-Th and small molecule p-DTS(FBTTh2)2 as donors and non-fullerene molecule IEICO-4F as an acceptor. It is observed that the power conversion efficiency (PCE) of ～10.9% for PTB7-Th: p-DTS(FBTTh2)2: IEICO-4F ternary OSCs with 15 wt% of p-DTS(FBTTh2)2 SM is higher than PCE of ～9.8% for PTB7-Th: IEICO-4F OSCs. Morphological studies confirm that the addition of p-DTS(FBTTh2)2 SM in PTB7-Th: IEICO-4F binary blend improves molecular ordering and crystallinity of PTB7-Th due to the favorable interaction with p-DTS(FBTTh2)2 thereby providing 3-D textured structures consisting of a mixture of edge-on and face-on orientations. The improved molecular ordering is shown to enhance exciton generation rate, exciton dissociation, charge collection, and to reduce charge recombination, all of which boosts the PCE.
关键词： PTB7-Th,Ternary,p-DTS(FBTTh2)2,IEICO-4F,GIWAXS,Non-fullerene
更新于2025-09-23 15:19:57
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Numerical modelling of non-fullerene organic solar cell with high dielectric constant ITIC-OE acceptor
摘要： The low dielectric constant of organic semiconductors has been a limiting factor in the organic photovoltaics. Non-Fullerene Acceptor Bulk Heterojunction (NFA-BHJ) organic solar cells with high dielectric constant acceptors have been gaining a lot of attention. No simulation work has been done on NFA-BHJ organic solar cell with a high dielectric constant acceptor so far to study the influence of various material parameters on the device performance. In this work, a comprehensive device modelling of the conventional structure of NFA-BHJ with poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b]dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c]dithiophene-4,8-dione)] (PBDB-T)as the polymer donor and (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetraki(4-hexylphenyl)-dithieno [2,3-d:2,3-d]-s-indaceno [1,2-b:5,6-b]dithiophene)) with Oligo-Ethylene side chain (ITIC-OE) as the non-fullerene acceptor is performed. We did a detailed analysis on the impact of technological parameters on the cell performance and optimized the device characteristics to produce improved efficiency. Numerical simulation is done using SCAPS 1-D program and the validity of simulated output has been verified by comparing with the measurements from reported literature. Optimization of the device parameters produced an improved device performance with an open circuit voltage of 0.9562 V, short circuit current density of mA/cm2, Fill factor of 69.75 % and a power conversion efficiency of 11%. The results are encouraging to develop NFA-BHJ organic solar cells with high dielectric constant acceptors in the near future.
关键词： numerical modelling,Non-Fullerene Acceptor Bulk Heterojunction,high dielectric constant,ITIC-OE acceptor,organic solar cells
更新于2025-09-23 15:19:57
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15.3% efficiency all-small-molecule organic solar cells enabled by symmetric phenyl substitution; ???????ˉ1?§°??§è?ˉ??o???é￥°?????°??????é??è??15.3%?????¨?°? ????-??????o?¤aé?3è????μ?±?;
摘要： Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells (NFSM-OSCs) due to the anisotropic conjugated backbones of both donor and acceptor. Therefore, developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials, and thus, enable the optimization of blend morphology is of vital importance. In this study, a new donor molecule B1, comprising phenyl-substituted benzo-dithiophene (BDT) central unit, exhibits strong interaction with the non-fullerene acceptor BO-4Cl in comparison with its corresponding thiophene-substituted BDT-based material, BTR. As a result, the B1 is affected and induced from an edge-on to a face-on orientation by the acceptor, while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results. It means the donor-acceptor blend morphology is synergistically optimized in the B1 system, and the B1:BO-4Cl-based devices achieve an outstanding power conversion efficiency (PCE) of 15.3%, further certified to be 15.1% by the National Institute of Me-trology, China. Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system, leading to the high-performance NFSM-OSCs.
关键词： all-small-molecule,intermolecular interaction,crystallinity,organic solar cells,non-fullerene
更新于2025-09-23 15:19:57
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Ultrafast spectroscopic investigation of the effect of solvent additives on charge photogeneration and recombination dynamics in non-fullerene organic photovoltaic blends
摘要： The PBDB-TF:IT-4F blend is a kind of state-of-the-art non-fullerene photovoltaic blend. Herein, the effects of 1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN) additives on the neat and blend film morphologies and the related ultrafast photophysical processes are studied. It is found that both DIO and CN can lead to an enhanced structural order in the in-plane direction and increased average lifetime of excitons in neat PBDB-TF films. The face-on orientation of PBDB-TF still exists in the DIO-processed PBDB-TF:IT-4F blend film, while in the case of the CN-processed blend film, molecular packing orientation is similar to that of the pristine blend film. The blend samples prepared with the two additives show increased initial exciton yields. Interestingly, in the blend samples prepared with the DIO additive, the recombination loss via the formation of polymer triplet excitons can be effectively suppressed, in comparison to the pristine and CN-processed samples. Both the DIO- and CN-processed devices show increased short-circuit current densities. The DIO-processed device is also found to have a superior fill factor due to suppressed recombination loss. The work provides a comprehensive insight into the ultrafast photophysical processes in varied blend morphologies induced by additives and their effect on the photovoltaic parameters of the devices.
关键词： charge photogeneration,ultrafast spectroscopy,recombination dynamics,solvent additives,non-fullerene photovoltaic blend
更新于2025-09-23 15:19:57
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High Sensitivity Visible-Near Infrared Organic Photodetector Based on Non-fullerene Acceptor
摘要： Highly sensitive solution-processed organic photodetectors (OPDs) with a broadband response ranging from visible to near infrared (NIR) and excellent overall device performance are demonstrated. The OPDs were fabricated from a blend consisting of a wide bandgap polymer donor and a newly developed fused octacylic small-molecule electron acceptor with acceptor–donor–acceptor structure, which shows relatively high and balanced hole/electron mobility and allow for thicker photoactive layer (~300 nm). In conjunction with the use of an optimized inverted device structure, the dark current density of the OPDs was suppressed to an ultralow level of (8.3±5.5)×10-10A cm-2 at bias of –1 V and the capability to directly weak light intensity is down to 0.24 pW cm?2, both are among the lowest reported values for OPDs. Owing to the low shot noise enabled by the inverted structure and the low thermal noise due to the high shunt resistance of the device, the obtained OPDs shows spectrally flat photoresponse in the range of 350–950 nm (UV-Vis-NIR) and a maximal specific detectivity (D*) of (2.1±0.1)×1013 Jones at 800–900 nm, which is among the best results of NIR OPDs reported to date and represents a highly sensitive photodetector for weak optical signal detection. Besides, the OPDs shows a wide bandwidth of 30 kHz, fast temporal response time around 12 us ~14 us and a large linear dynamic range of 106 dB.
关键词： dark current density,specific detectivity,non-fullerene acceptors,weak optical signal detection,organic photodetectors
更新于2025-09-23 15:19:57