Vertical Phase Regulation with 1,3,5‐Tribromobenzene Leads to 18.5% Efficiency Binary Organic Solar Cells

• DOI: 10.1002/advs.202303150
• Publication Date: 2023-07-10T03:20:15Z
• Authors: Chaofeng Zhu; Sein Chung; Jingjing Zhao; Yuqing Sun; Bin Zhao; Zhenmin Zhao; Seunghyun Kim; Kilwon Cho; Zhipeng Kan
• Keywords: Acceptor; Photoactive layer; Charge carrier

The sequential deposition method assists the vertical phase distribution in photoactive layer of organic solar cells, enhancing power conversion efficiencies. With this film coating approach, morphology both layers can be fine-tuned with high boiling solvent additives, as frequently applied one-step casting films. However, introducing liquid additives compromise morphological stability devices due to residuals. Herein, 1,3,5-tribromobenzene (TBB) volatility and low cost, is used a solid additive acceptor solution combined thermal annealing regulate cells composed D18-Cl/L8-BO. Compared control treated TBB those that underwent additional processing exhibit increased exciton generation rate, charge carrier mobility, lifetime, reduced bimolecular recombination. As result, TBB-treated achieve champion efficiency 18.5% (18.1% averaged), one highest efficiencies binary open circuit voltage exceeding 900 mV. This study ascribes advanced device performance gradient-distributed donor-acceptor concentrations direction. findings provide guidelines for optimizing sequentially deposited top high-performance cells.