Unprecedented short-circuit current density and efficiency of vacuum- deposited organic solar cells based on 8H-thieno[2,3:4,5]thieno[3,2-b] thieno[2,3-d]pyrrole

초록

Despite the many advantages for industrial mass production, vacuum-deposited organic solar cells (OSCs) suffer from low efficiency, primarily due to the limited molecular library of small-molecule donor and acceptor materials, which remains a significant challenge. Herein, two donor-acceptor-acceptor (DA-A)-configured small-molecule donors, named TTBTDC and TTBTDC-F were synthesized, using 8H-thi eno[2 ,3 :4,5]thieno[3,2-b]thieno[2,3-d]pyrrole (TTP) as a new fused-ring donor unit. Benefiting from the strong electron-donating ability of the TTP moiety and the adoption of the D-A-A molecular configuration, these molecules exhibited strong visible and near-infrared absorption as well as deep-lying highest occupied molecular orbital (HOMO) energy levels. Consequently, OSCs based on TTBTDC achieved an unprecedented power conversion efficiency (PCE) of 10.28% (certified value of 10.05%) with a shortcircuit current density (Jsc) up to 17.78 mA cm 2 , representing the highest PCE and Jscvalues reported to date for vacuum-deposited OSCs. In contrast, OSCs based on TTBTDC-F exhibited an inferior PCE of 8% with slightly higher open-circuit voltage (Voc) but lower Jsc. By systematically investigating the relationships between molecular structure and properties, we found that the high performance of TTBTDC devices results from extended absorption up to 900 nm, stronger cofacial antiparallel it-it interactions, and superior charge transport with suppressed recombination. Besides, both TTBTDC and TTBTDC-F devices exhibited excellent device stabilities, including storage stability, thermal stability, and photo- stability. This work demonstrates the great potential of TTP as a building block for constructing small- molecule donors and sheds light on the molecular design of small-molecule donors for high-efficiency and stable vacuum-deposited OSCs. (c) 2025 Science China Press. Published by Elsevier B.V. and Science China Press. All rights are reserved,

키워드