Improved Charge Generation via Ultrafast Effective Hole‐Transfer in All‐Polymer Photovoltaic Blends with Large Highest Occupied Molecular Orbital (HOMO) Energy Offset and Proper Crystal Orientation

• DOI: 10.1002/adfm.201801611
• Publication Date: 2018-06-13T05:46:50Z
• Authors: Feng Jin; Jianyu Yuan; Wenping Guo; Yalong Xu; Yannan Zhang; Chuanxiang Sheng; Wanli Ma; Haibin Zhao
• Keywords: Acceptor; Quantum Efficiency

Abstract Improved charge generation via fast and effective hole transfer in all‐polymer solar cells (all‐PSCs) with large highest occupied molecular orbital (HOMO) energy offset (Δ E H ) is revealed utilizing ultrafast transient absorption (TA) spectroscopy. Blending the same nonfullerene acceptor poly{[ N , ′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene) (N2200) three different donor polymers produces blends Δ . The selective excitation of N2200 component enables to uncover process from polaron‐induced bleaching signals probed at wavelength. As enhanced 0.14 0.37 eV, rate rises more than one order efficiency increases 12.9% 86.8%, agreement trend internal quantum infrared region where only has absorption. Additionally, Grazing‐incidence wide‐angle X‐ray scattering measurements indicate that face‐on crystal orientation both polymer also plays an important role facilitating all‐PSCs. Hence, proper should be considered material design for efficient N2200‐based heterostructures. These results can provide valuable guidance fabrication all‐PSCs further improve power conversion efficiency.