Low‐Work‐Function PEDOT Formula as a Stable Interlayer and Cathode for Organic Solar Cells
Tiefeng Liu, Lulu Sun, Xinyun Dong, Youyu Jiang, Wen Wang, Cong Xie, Wenwu Zeng, Yang Liu, Fei Qin, Lu Hu, Yinhua Zhou
Abstract
Abstract Cathode with low work‐function (WF) is a vital unit in optoelectronic devices. Yet, the stable cathode is still a big challenge. Here, PEDOT:PSS‐TBA is reported among series of PEDOT:PSS‐M, where PEDOT:PSS denotes poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate), M refers to monovalent cation and TBA is tetrabutylammonium specifically, as a stable cathode. The PEDOT:PSS‐TBA is synthesized via ion exchange with WF of 4.1–4.2 eV and its conductivity can be improved to 300 S cm −1 by the additive. Meanwhile, PEDOT:PSS‐TBA is stable even under plasma, heat, or isopropanol sonication. Organic solar cells (OSCs) are fabricated with indium tin oxide (ITO)/PEDOT:PSS‐TBA and highly conductive PEDOT:PSS‐TBA (with additive, hc ‐PEDOT:PSS) electrodes respectively. The OSCs display superior stability than the reference with ITO/ZnO as the cathode. As a proof of concept, solution‐processed OSCs are demonstrated with a three‐layered structure ( hc ‐PEDOT:PSS‐TBA/active layer/PEDOT:PSS), which proves PEDOT:PSS‐TBA as a promising cathode for printable optoelectronic with a simplified structure.