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.
The latest development in perovskite solar cell (PSC) technology has been significantly influenced by advanced techniques aimed at passivating surface defects. This work presents a new approach called thermal imprinting-assisted ion exchange passivation (TIAIEP), which delivers a different approach to conventional solution-based methods. TIAIEP focuses on addressing surface imperfections in solid-state films by using a passivator that promotes ion exchange specifically at the defect sites within the perovskite layer. By adjusting the time and temperature of the TIAIEP process, we achieve substantial enhancement in the creation of a compositional gradient within the films. This optimization slows the cooling rate of hot carriers, leading to minimizing charge recombination and improving the device performance. Remarkably, devices treated with TIAIEP achieve a 22.29% power conversion efficiency and show outstanding stability, with unencapsulated PSCs maintaining 91% of their original efficiency after over 2000 h of storage and 90% efficiency after 1200 h of constant illumination. These results highlight TIAIEP's effectiveness in mitigating surface defects, improving both the photoelectric and stability performance of PSCs, and indicating significant potential for large-scale application in perovskite film passivation, promoting the widespread adoption of this technology.
Perovskite solar cells (PSCs) have achieved impressive efficiency, but their commercialization is limited by issues like chemical homogeneity within the perovskite films, leading to defects and phase segregation, which severely compromise the stability and performance of PSCs. This study presents a novel approach to overcoming these barriers by employing N,N-methylenebisacrylamide (MBA) as a multifunctional crosslinking agent within the perovskite structure. MBA enhances chemical uniformity both laterally and vertically, improves crystallinity, and boosts overall film stability by forming a robust crosslinked network that regulates nucleation and growth dynamics during the pre-seeding process. This modification ensures a uniform distribution within the perovskite matrix and significantly reduces defect densities. As a result, MBA-treated PSCs achieved a notable improvement in power conversion efficiency (PCE), reaching up to 24.26%, compared to 22.64% in control devices. Additionally, the MBA-modified devices demonstrated remarkable stability, maintaining 90% of their initial efficiency after 1200 h of continuous illumination, in contrast to the 50% efficiency loss observed in control devices after just 500 h. These findings underscore the transformative potential of MBA as an additive in PSCs, offering a viable pathway to not only enhance efficiency but also significantly improve the long-term stability of these devices, thus bringing PSCs closer to commercial viability.