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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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Cyclopentadithiophene cored A-π-D-π-A non-fullerene electron acceptor in ternary polymer solar cells to extend the light absorption up to 900?nm
摘要： Conjugated small molecular non-fullerene electron acceptors (NFA) are considered as one of the critical materials for achieving high performance and low cost of polymer solar cells, and received much attention in the last few years. However, most of the NFAs are based on large fused π-aromatic core, which requires complicate synthesis efforts. In addition, the relatively weak light absorption limited to 800 nm of most the NAFs limits the energy harvesting capability of the solar cells. In this paper, we report an A-π-D-π-A type molecule cored with a cyclopentadithiophene unit, which can be easily synthesized in two steps from commercially available starting materials. This compound shows a broad absorption up to 900 nm in thin solid film, which is ascribed to the relatively high highest occupied molecular orbital (HOMO) energy level as confirmed by cyclic voltammery and theoratical calculation. Application of the compound in polymer solar cells was also investigated both in binary and in ternary systems. The optimized power conversion efficiency (PCE) in binary solar cell with PTB7-Th as donor is 5.76% with an open circuit voltage (VOC) of 0.838 V, a short circuit current (JSC) of 14.81 mA/cm2 and a fill factor (FF) of 46.4%. In the ternary solar cells which includes a second acceptor, PC71BM, the highest PCE achieved is 9.39% with a VOC of 0.803 V, a JSC of 19.01 mA/cm2, a FF of 61.6%, which is over 20% enhancement compared to the PTB7-Th:PC71BM system (PCE of 7.58%). This work develops a simple small molecule non-fullerene acceptor which can largely enhance the photo response in near infrared region to improve the performance of fullerene based organic solar cell.
关键词： Light absorption,Non-fullerene electron acceptor,Cyclopentadithiophene,Ternary systems,Polymer solar cells
更新于2025-09-12 10:27:22
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New cyclopentadithiophene-based (X-DAD′AD)n conjugated polymers for organic solar cells
摘要： Five new donor-acceptor (X-DAD'AD)n type conjugated polymers have been synthesized using different X blocks based on carbazole, fluorene, silafluorene, benzodithiophene, and cyclopentadithiophene (CPDT). The strongly electron donating CPDT unit was used as a central D′ fragment to enhance intramolecular charge transfer interactions along the polymer backbone and reduce the bandgap of the resulting conjugated polymers. Apparently, the nature of the X block impacts the photophysical, morphological and optoelectronic properties of the designed polymers as well as their performance in bulk heterojunction solar cells. Fluorene-based copolymer P2 in combination with [70]PCBM delivered the best power conversion efficiency of 5.0% with a VOC of 0.78 V, a JSC of 11.1 mA/cm2 and a FF of 57%. Possibility for easy variation of the X and D′ blocks in the designed materials paves a way towards design of a variety of new materials for optoelectronic applications.
关键词： Photovoltaics,Conjugated polymers,Cyclopentadithiophene,Organic solar cells
更新于2025-09-11 14:15:04