Versatile Device Architectures for High-Performing Light-Soaking-Free Inverted Polymer Solar Cells

Yu Yan; Feilong Cai; Liyan Yang; Wei Li; Yanyan Gong; Jinlong Cai; Shuang Liu; Robert S Gurney; Dan Liu; Tao Wang

doi:10.1021/acsami.7b08130

Versatile Device Architectures for High-Performing Light-Soaking-Free Inverted Polymer Solar Cells

ACS Appl Mater Interfaces. 2017 Sep 27;9(38):32678-32687. doi: 10.1021/acsami.7b08130. Epub 2017 Sep 13.

Authors

Yu Yan¹, Feilong Cai¹, Liyan Yang¹, Wei Li¹, Yanyan Gong¹, Jinlong Cai¹, Shuang Liu¹, Robert S Gurney¹, Dan Liu¹, Tao Wang¹

Affiliation

¹ School of Materials Science and Engineering and ‡State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology , Wuhan 430070, China.

PMID: 28870067
DOI: 10.1021/acsami.7b08130

Abstract

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 TiO₂ 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:PC₇₁BM solar cells with efficiencies of over 10%, by adding PEI either in the bulk or as an adjacent layer below or above the TiO₂ ETL.

Keywords: PEI; PFN-OX; TiO2; light-soaking; polymer solar cells.