School of Materials Science and Engineering and ‡State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology , Wuhan 430070, China.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):32678-32687. doi: 10.1021/acsami.7b08130. Epub 2017 Sep 13.
Metal oxide charge transport layers have been widely employed to prepare inverted polymer solar cells with high efficiency and long lifetime. However, the intrinsic defects in the metal oxide layers, especially those prepared from low-temperature routes, overshadow the high efficiency that can be achieved and also introduce "light-soaking" issues to these devices. In this work, we have employed polyethyleneimine (PEI) and poly(9,9-bis(6'-(N,N-diethylamino)propyl)-fluorene-alt-9,9-bis-(3-ethyl(oxetane-3-ethyloxy)-hexyl)-fluorene] (PFN-OX) to modify our low-temperature-processed TiO electron transport layer (ETL) and demonstrated that the light-soaking issue can be effectively eliminated by PEI modifications because of the formation of abundant dipole moments, whereas PFN-OX was ineffective as a result of deficient dipole moments at the interface. Excitingly, PEI modifications enable versatile device architectures to obtain light-soaking-free, inverted PTB7-Th:PCBM solar cells with efficiencies of over 10%, by adding PEI either in the bulk or as an adjacent layer below or above the TiO ETL.
金属氧化物电荷传输层已被广泛用于制备高效率、长寿命的倒置聚合物太阳能电池。然而，金属氧化物层中存在固有缺陷，尤其是那些通过低温路线制备的层，这降低了可以实现的效率，并为这些器件引入了“光致衰减”问题。在这项工作中，我们使用聚乙烯亚胺（PEI）和聚[9,9-双（6'-（N，N-二乙基氨基）丙基）芴-9,9-双（3-乙基（氧杂环丁烷-3-乙氧基）己基）芴]（PFN-OX）来修饰我们低温处理的 TiO 电子传输层（ETL），并证明 PEI 修饰可以有效地消除光致衰减问题，因为形成了丰富的偶极矩，而 PFN-OX 则无效，因为界面处缺乏偶极矩。令人兴奋的是，PEI 修饰通过在体相或在 TiO ETL 下方或上方作为相邻层添加 PEI，使各种器件结构能够获得无光致衰减的倒置 PTB7-Th：PCBM 太阳能电池，效率超过 10%。
