Improving the Stability of Non-fullerene-Based Organic Photovoltaics through Sequential Deposition and Utilization of a Quasi-orthogonal Solvent

Abstract

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.

Printing and Coating Techniques for Scalable Organic Photovoltaic Fabrication

“…There have been few papers that aim at improving the printing technique themselves, either during or post deposition. Such techniques including the heating of the substrate/printing head [ 63 , 84 ], use of air/nitrogen to improve coating uniformity [ 137 ], and influencing the printing quality by the choice of solvent, combination, and additives, which all have an impact on influencing the printing quality [ 41 , 175 ]. This is especially true with blade coating, where the combination of in situ annealing [ 84 , 137 , 140 , 141 , 145 , 151 , 152 , 153 ] and the use of hot airflow [ 84 , 137 ] allowed for large-area and high-performing OPVs.…”

“…Nowadays, there is a shift towards pseudo-bilayers [ 10 , 39 ] and sequentially deposited [ 15 , 40 , 41 , 42 ] active layers. The advantage of this approach is that it enables better control over the interfacial area between the donor and acceptor, depending on the solvent used in the top active material ink and film processing.…”

Advances in layer-by-layer processing for efficient and reliable organic solar cells

“…The same group demonstrated enhanced thermal stability of LBL OSCs by using 1-CN + DCM as a quasi-orthogonal solvent for the deposition of the Y6 acceptor layer. 198 This solvent mixture had a lower vapor pressure, which facilitated the dissolution and diffusion of the Y6 into the PM6 donor layer without compromising its film quality. The crystallinity of the BHJ interlayer increased in the donor domain resulting in a PCE of 14.1% with high thermal stability.…”

Enhancing Reproducibility in Organic Solar Cell Fabrication via Static Sequential Deposition with Cross-Linked Polymer Donor and Nonfullerene Acceptor

“…To address this issue, static coating and orthogonal solvents have commonly been employed . The static coating process involves depositing a second layer solution (the acceptor solution) onto the previously deposited donor layer and then spinning the substrate.…”