The development of organic photovoltaic (OPV) devices
based on
non-fullerene acceptors (NFAs) has led to a rapid improvement in their
efficiency. Despite these improvements, significant performance degradation
in the early stages of operation, known as burn-in, remains a challenge
for NFA-based OPVs. To address this challenge, this study demonstrates
a stable NFA-based OPV fabricated using sequential deposition (SqD)
and a quasi-orthogonal solvent. The quasi-orthogonal solvent, which
is prepared by incorporating 1-chloronaphthalene (1-CN) into dichloromethane
(DCM), reduces the vapor pressure of the solvent and allows for the
efficient dissolution and penetration of the Y6 (one of efficient
NFAs) into a PM6 polymer-donor layer without damaging the latter.
The resulting bulk heterojunction (BHJ) is characterized by a higher
degree of crystallinity in the PM6 domains than that prepared using
a conventional single-step deposition (SD) process. The OPV fabricated
using the SqD process exhibits a PCE of 14.1% and demonstrates superior
thermal stability to the SD-processed OPV. This study conclusively
reveals that the formation of a thermally stable interface between
the photoactive layer and the electron-transport layer (ETL) is the
primary factor contributing to the high thermal stability observed
in the SqD-processed OPV.