High-performance and scalable large-area organic solar cells enabled by alloy-like composite-induced optimized morphology processed from non-halogenated solvent in air
Muhammad Jahankhan, Du Hyeon Ryu, Dongchan Lee, Sabeen Zahra, Sobirkhon Atavullaev, Seungjin Lee, Bumjoon J. Kim, Jianhui Hou, Hong Zhang, Shinuk Cho, Won Suk Shin, Chang Eun Song
Abstract
• Scalable, eco-friendly OSCs enabled by alloy-like blends of low- and high-crystalline small molecule acceptors. • Ternary system shows strong tolerance to thickness/area variations and excellent stability under light and heat. • Achieved > 69.7% FF and > 14.2% PCE in large-area OSCs (up to 55.0 cm²) with minimal cell-to-module efficiency loss. This study presents a scalable and eco-friendly approach for high-performance organic solar cells (OSCs) by optimizing photoactive morphology with an alloy-like composite structure between small molecule acceptors (SMAs). Processing the photoactive film in ambient conditions using non-halogenated solvents, we address key challenges in efficiency, scalability, stability, and environmental impact for commercially available OSCs. The unique combination of low- and high-crystalline SMAs offers a balanced and refined bulk-heterojunction morphology that enhances charge transfer/transport, reduces recombination/energy losses, and yields high/balanced carrier mobility. The low-crystalline acceptor (Y6-HU) provides flexibility to the molecular arrangement, while the high-crystalline component (BTP-eC9) establishes ordered charge transport pathways. This synergy leads to improved tolerance to photoactive thickness/area variations, enhanced batch-to-batch reproducibility, and outstanding device stability under light and thermal exposure, enabling consistent fill factors over 69.7 % and power conversion efficiencies over 14.2 % across large-area OSCs up to 55.0 cm 2 with minimal cell-to-module efficiency loss. These photovoltaic parameters are among the highest values ever achieved for OSCs fabricated via a spin-coating-free process using non-halogenated solvents. Our strategy achieves high efficiency and stability while ensuring environmental sustainability, advancing OSC technology for scalable, eco-friendly photovoltaic solutions in diverse applications.