Small-molecular iridium complex based organic solar cells (OSCs) show inferior power conversion efficiencies (PCEs) to those of pure organic/polymer analogues. To further improve the performance of such OSCs, we reported a bilayer device structure, which was fabricated by sequentially spin-coating a p-type polymer semiconductor (poly[4,4′-bis(2-butyloctoxycarbonyl-[2,2′-bithiophene]-5,5-diyl)-alt-(2,2′bithiophene-5,5′diyl)]) (PDCBT) layer and a bulk-heterojunction (BHJ) layer with the cyclometalated Ir complex (TBzIr) as the donor and PC₇₁BM as the acceptor. Compared to the original TBzIr:PC₇₁BM BHJ device, the bilayer PDCBT/TBzIr:PC₇₁BM structure exhibited an identical high open circuit voltage of 0.92 V, and increased both short circuit current from 9.25 to 11.14 mA cm⁻² and fill factor from 0.46 to 0.61. The p-type PDCBT layer was inserted to afford increased light absorption, assist the upper BHJ blends to form optimized morphologies, and provide supplementary donor–acceptor interfaces to facilitate exciton dissociation. Therefore, the PCE could be significantly improved from 3.91% for TBzIr:PC₇₁BM to 6.17% for PDCBT/TBzIr:PC₇₁BM. To the best of our knowledge, this is the highest efficiency ever reported for small-molecular Ir complex based organic solar cells.

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通过优化器件提高光伏性能的基于小分子铱配合物的有机太阳能电池

基于小分子铱配合物的有机太阳能电池（OSC）的功率转换效率（PCE）低于纯有机/聚合物类似物的功率转换效率。为了进一步改善此类OSC的性能，我们报道了一种双层器件结构，该结构是通过依次旋涂p型聚合物半导体（聚[4,4'-双（2-丁基辛氧基羰基-[2,2'-噻吩] -5,5-二基） - ALT - （2,2'bithiophene-5,5'diyl）]）作为（PDCBT）层和与所述环金属化Ir络合物（TBzIr体异质结（BHJ）层）供体，PC ₇₁ BM作为受体。与原始TBzIr：PC ₇₁ BM BHJ设备相比，双层PDCBT / TBzIr：PC ₇₁BM结构表现出相同的0.92 V高开路电压，短路电流从9.25 mA cm ^-2增加到11.14 mA cm ^-2，填充系数从0.46增加到0.61。插入p型PDCBT层可增加光吸收，帮助上部BHJ共混物形成最佳形态，并提供辅助供体-受体界面以促进激子解离。因此，PCE可以从TBzIr：PC ₇₁ BM的3.91％显着提高到PDCBT / TBzIr：PC ₇₁ BM的6.17％。据我们所知，这是有报道的基于小分子Ir配合物的有机太阳能电池的最高效率。