摘要/Abstract

最近，有机太阳能电池中三元策略的出现使得高能量转化效率和简便的器件制备方式有望同时实现.大量实验证明，通过构造三元有机太阳能电池可以实现吸光互补以提高电流或者在能级间形成级联以提高开压.设计并合成了以并噻吩取代卟啉为核，通过炔键连接二酮吡咯并吡咯末端基团的新分子，命名为DEP-TT，该分子有较小的能带间隙（1.31 eV），光谱吸收可达898 nm.以该卟啉分子为给体，富勒烯PC₇₁BM为受体制备双组分有机太阳能电池，效率可达7.46%，但开压相对较低（0.75 V）.进一步研究发现，加入10%的富勒烯衍生物ICBA制备三元有机太阳能电池，效率可增大至8.15%，这是基于卟啉小分子为给体的有机太阳能电池取得相对较高效率的器件之一.由于PCBM和ICBA两组分间形成级联能级和协同作用，器件效率明显提高，这意味着三元有机太阳能电池的构建可以同时提高开压和电流，从而实现器件效率的全面提高.
关键词: 卟啉小分子给体, 双组分富勒烯受体, 三元有机太阳能电池
Recently, ternary organic solar cells have emerged as a promising strategy to achieve both high performance and fabrication simplicity for organic solar cells. It has been proved that this strategy is an effective way to achieve improved short-circuit current density (J_sc) with complementary absorption or to get enhanced open-circuit voltage (V_oc) through forming energy level cascade. In this work, we designed and synthesized a thieno[3,2-b]thiphene-substituted porphyrin molecule flanked with two diketopyrrolopyrrole units by ethynylene bridges, named DEP-TT, which exhibited a very low energy bandgap of 1.31 eV and a broad light absorption to 898 nm. The power conversion efficiency (PCE) of binary devices based on DEP-TT and the acceptor [6,6]-phenyl-C71-butyric-acid-methyl-ester (PC₇₁BM) achieved 7.46% with a relatively low V_oc of 0.75 V. Futhermore, the ternary solar cells with 10% indene-C60 bis-adduct (ICBA) achieved high PCE of 8.15%, with higher V_oc, J_sc and a relatively higher PCE based on organic solar cells with a porphyrin-small molecule as the donor. This improved performance is believed to be due to the energy level cascade and synergistic effects of the two acceptors of PCBM and ICBA, which suggestes that the ternary bulk heterojunction (BHJ) strategy is a promising way to improve both V_oc and J_sc simultaneously and thus overall performance for the same donor material.
Key words: porphyrin small molecule donor, two fullerene acceptors, ternary organic solar cell


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