State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC) , Chengdu 610054, P. R. China.
Department of Chemical and Environmental Engineering, Yale University , New Haven, Connecticut 06511, United States.
ACS Appl Mater Interfaces. 2016 Jun 22;8(24):15724-31. doi: 10.1021/acsami.6b03453. Epub 2016 Jun 10.
The development of thick organic photovoltaics (OPV) could increase absorption in the active layer and ease manufacturing constraints in large-scale solar panel production. However, the efficiencies of most low-bandgap OPVs decrease substantially when the active layers exceed ∼100 nm in thickness (because of low crystallinity and a short exciton diffusion length). Herein, we report the use of solvent additive diphenyl ether (DPE) that facilitates the fabrication of thick (180 nm) active layers and triples the power conversion efficiency (PCE) of conventional thienothiophene-co-benzodithiophene polymer (PTB7)-based OPVs from 1.75 to 6.19%. These results demonstrate a PCE 20% higher than those of conventional (PTB7)-based OPV devices using 1,8-diiodooctane. Morphology studies reveal that DPE promotes the formation of nanofibrillar networks and ordered packing of PTB7 in the active layer that facilitate charge transport over longer distances. We further demonstrate that DPE improves the fill factor and photocurrent collection by enhancing the overall optical absorption, reducing the series resistance, and suppressing bimolecular recombination.
厚有机光伏（OPV）的发展可以增加活性层的吸收，并缓解在大规模太阳能电池板生产中的制造限制。然而，当活性层厚度超过约 100nm 时，大多数低带隙 OPV 的效率会大幅下降（因为结晶度低和激子扩散长度短）。在此，我们报告了使用溶剂添加剂二苯醚（DPE），它可以促进厚（180nm）活性层的制备，并将传统噻吩并噻吩-苯并二噻吩聚合物（PTB7）基 OPV 的功率转换效率（PCE）从 1.75 提高到 6.19%。这些结果表明，与使用 1,8-二碘辛烷的传统（PTB7）基 OPV 器件相比，PCE 提高了 20%。形貌研究表明，DPE 促进了活性层中纳米纤维网络和 PTB7 的有序堆积的形成，这有利于电荷在更长距离上的传输。我们进一步证明，DPE 通过增强整体光吸收、降低串联电阻和抑制双分子复合，提高了填充因子和光电流收集。
