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Significantly Enhanced Molecular Stacking in Ternary Bulk Heterojunctions Enabled by an Appropriate Side Group on Donor Polymer
摘要： Ternary strategy is a promising approach to broaden the photoresponse of polymer solar cells (PSCs) by adopting combinatory photoactive blends. However, it could lead to a more complicated situation in manipulating the bulk morphology. Achieving an ideal morphology that enhances the charge transport and light absorption simultaneously is an essential avenue to promote the device performance. Herein, two polymers with different lengths of side groups (P1 is based on phenyl side group and P2 is based on biphenyl side group) are adopted in the dual-acceptor ternary systems to evaluate the relationship between conjugated side group and crystalline behavior in the ternary system. The P1 ternary system delivers a greatly improved power conversion efficiency (PCE) of 13.06%, which could be attributed to the intense and broad photoresponse and improved charge transport originating from the improved crystallinity. Inversely, the P2 ternary device only exhibits a poor PCE of 8.97%, where the decreased device performance could mainly be ascribed to the disturbed molecular stacking of the components originating from the overlong conjugated side group. The results demonstrate a conjugated side group could greatly determine the device performance by tuning the crystallinity of components in ternary systems.
关键词： ternary systems,ternary bulk heterojunctions,complementary absorption,polymer solar cells,molecular stacking,side chain effect
更新于2025-09-23 15:19:57
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A New Wide Bandgap Donor Polymer for Efficient Nonfullerene Organic Solar Cells with a Large Open‐Circuit Voltage
摘要： Significant progress has been made in nonfullerene small molecule acceptors (NF-SMAs) that leads to a consistent increase of power conversion efficiency (PCE) of nonfullerene organic solar cells (NF-OSCs). To achieve better compatibility with high-performance NF-SMAs, the direction of molecular design for donor polymers is toward wide bandgap (WBG), tailored properties, and preferentially ecofriendly processability for device fabrication. Here, a weak acceptor unit, methyl 2,5-dibromo-4-fluorothiophene-3-carboxylate (FE-T), is synthesized and copolymerized with benzo[1,2-b:4,5-b′]-dithiophene (BDT) to afford a series of nonhalogenated solvent processable WBG polymers P1-P3 with a distinct side chain on FE-T. The incorporation of FE-T leads to polymers with a deep highest occupied molecular orbital (HOMO) level of ?5.60?5.70 eV, a complementary absorption to NF-SMAs, and a planar molecular conformation. When combined with the narrow bandgap acceptor ITIC-Th, the solar cell based on P1 with the shortest methyl chain on FE-T achieves a PCE of 11.39% with a large Voc of 1.01 V and a Jsc of 17.89 mA cm?2. Moreover, a PCE of 12.11% is attained for ternary cells based on WBG P1, narrow bandgap PTB7-Th, and acceptor IEICO-4F. These results demonstrate that the new FE-T is a highly promising acceptor unit to construct WBG polymers for efficient NF-OSCs.
关键词： complementary absorption,wide bandgap,donor polymers,nonfullerene organic solar cells,nonhalogenated solvents
更新于2025-09-19 17:13:59
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An all small molecule organic solar cell based on a porphyrin donor and a non-fullerene acceptor with complementary and broad absorption
摘要： A thieno[3,2-b]thiophene-functionalized porphyrin molecule (DEP-TT) with the ethynylene bridges between the diketopyrrolopyrrole and porphyrin units has been designed and synthesized as the donor material. DEP-TT exhibits a broad absorption wavelength in the visible region with the onset absorption to 898 nm of the film and a low optical band gap of 1.38 eV. IDT-C8, as the acceptor material has a relatively strong absorption spectrum ranging from 500-750 nm in the solid film, which exactly fills the absorption trough of DEP-TT. The power conversion efficiency (PCE) of all small molecule increased from 0.64% (Jsc = 2.61 mA cm-2, Voc = 0.82 V, and FF = 0.30) to 5.14% (Jsc = 11.15 mA cm-2, Voc = 0.71 V, and FF = 0.65) after solvent vapor annealing. The PCE of 5.14% provided valuable recommendation based on porphyrin all small molecule system, since few work has involved in this field.
关键词： organic solar cells,all small molecule,complementary absorption,porphyrin
更新于2025-09-16 10:30:52
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PbS quantum dot tandem solar cell based on solution-processed nanoparticle intermediate layer
摘要： Tandem cells are one of the most effective ways of breaking the single junction Shockley-Queisser limit. Solution-processable PbS quantum dots are good candidates for producing multiple junction solar cell due to their size-tunable bandgap. The intermediate recombination layer connecting the subcells in a tandem solar cell is crucial for device performance because it determines the charge recombination efficiency and electrical resistance. In this work, solution-processed ultra-thin NiO and Ag nanoparticle film serves as an intermediate layer to enhance the charge recombination efficiency in PbS QD dual-junction tandem solar cells. The champion devices with device architecture of ITO/S-ZnO/1.45 eV PbS-PbI2/PbS-EDT/NiO/Ag NP/ZnO NP/1.22 eV PbS-PbI2/PbS-EDT/Au delivers a 7.1% power conversion efficiency, which outperforms the optimized reference sub-cells. This result underscores the critical role of appropriate nanocrystalline recombination layer in producing high-performance solution-processed PbS QD tandem cells.
关键词： recombination layer,tandem solar cell,PbS quantum dots,complementary absorption,intermediate layer
更新于2025-09-12 10:27:22