title: Simultaneously Enhanced Efficiency and Stability of Polymer Solar Cells by Employing Solvent Additive and Upside-down Drying Method.
abstract: The morphology of active layer plays an important role in determining the power conversion efficiency (PCE) and stability of polymer solar cells (PSCs), which strongly depend on the dynamic drying process of active layer. In this work, an efficient and universal method was developed to let active layer undergo upside-down drying process in a covered glass Petri dish. For the PSCs based on PTB7-Th:PC71BM, the champion PCEs were improved from 8.58% to 9.64% by mixing 3 vol % 1,8-di-iodooctane and further to 10.30% by employing upside-down drying method. The enhanced PCEs of PSCs with active layers undergoing upside-down drying process are mainly attributed to the optimized vertical phase separation, the more ordered and tightly packed π-π stacking of polymer molecules. Meanwhile, PC71BM molecules can be frozen in more ordered and tightly packed π-π stacking polymer network, which lead to the enhanced stability of PSCs. The universality of upside-down drying method can be solidly confirmed from PSCs with PTB7:PC71BM, PffBT4T-2OD:PC71BM, or PBDT-TS1:PC71BM as active layers, respectively. The molecular packing and phase separation of blend films with different solvent additives and drying methods were investigated by grazing incidence X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy.
authors.affiliation: Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University , Beijing 100044, People's Republic of China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University , Beijing 100044, People's Republic of China.
authors.forename: Fujun
authors.identifier: http://orcid.org/0000-0003-2829-0735
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University , Beijing 100044, People's Republic of China.
authors.forename: Qiaoshi
authors.initials: Q
authors.lastname: An
authors.affiliation: Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University , Beijing 100044, People's Republic of China.
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University , Beijing 100044, People's Republic of China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Ma
authors.affiliation: School of Material Science and Technology, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology , 1 Jinji Road, Guilin, Guangxi 541004, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
keywords: drying method; efficiency; polymer solar cells; stability; upside-down