• Energy Research

AbstractImproving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis.

AbstractIn this work, the overarching goal of improving the photooxidative stability of organic components used in photovoltaic devices is addressed, focusing on the common problem of degradation mediated by singlet molecular oxygen. Through a systematic exploration of boron subphthalocyanines (SubPcs), the influence of donor and acceptor substituents on the SubPc's redox properties has been examined, including the SubPc's ability to (1) act as a photosensitizer for singlet oxygen generation and (2) deactivate singlet oxygen are examined. How singlet oxygen formation and removal are influenced by linking together three SubPcs in a compact structure and by linking a SubPc to another molecular unit of relevance for organic photovoltaics (indenofluorene‐extended tetrathiafulvalene) is also examined. Synthetic protocols rooted in acetylenic scaffolding, experimental and computational structure–property relationships (optical and redox properties, singlet oxygen quantum yields, and removal kinetics), and characteristics of a functional photovoltaic device using a SubPc molecule are presented, demonstrating that cyano functionalization results in remarkably enhanced organic photovoltaic device stability.

The development of nonfullerene acceptors (NFAs) has led to dramatic improvements in the device efficiencies of organic photovoltaic (OPV) cells. To date it is, however, still unclear how those laboratory‐scale efficiencies transfer to commercial modules, and how stable these devices will be when processed via industrially compatible methods. Herein, the degradation behavior of lab‐scale and scalable OPV devices using similar nonfullerene‐based active layers is assessed. It is demonstrated that the scalable NFA OPV exhibits completely reversible degradation when assessed in ISOS‐O‐1 outdoor conditions, which is in contrast to the laboratory‐scale devices assessed via the indoor ISOS‐L‐2 protocol. Results from transient photovoltage (TPV) indicate the presence of charge trap formation, and a number of potential mechanisms are proposed for the selective occurrence of this in laboratory‐scale devices tested in ISOS‐L laboratory conditions—ultimately concluding that it has its origins in the different device architectures used. The study points at the risk of assessing active layer stability from laboratory‐scale devices and degradation studies alone and highlights the importance of using a diverse range of testing conditions and ISOS protocols for such assessment.

Correction for ‘Enhancing organic solar cell lifetime through humidity control using BCF in PM6 : Y6 active layers’ by Kaike Pacheco et al., Sustainable Energy Fuels, 2024, https://doi.org/10.1039/D4SE00598H.

Boosting organic solar cell lifetime with BCF doping for improved stability.

We propose a new approach for assessing the lifetimes of perovskite photovoltaics based on daily energy output which accounts for reversible diurnal changes.