Stability of non-fullerene organic solar cells: a device engineering perspective

Organic solar cells (OSCs) have recently achieved remarkable power conversion efficiencies of over 20% in single-junction configurations. Despite this rapid progress, their practical deployment remains constrained by insufficient operational stability. This review systematically examines the intrinsic and extrinsic degradation mechanisms in OSCs from a device engineering standpoint, covering issues such as metastable morphology in the active layer, interfacial interdiffusion, vulnerability to environmental stressors (e.g., oxygen, moisture), and mechanical failures. We critically assess recent device-level stabilization approaches, with particular emphasis on the design of robust multi-component active layers, the adoption of inverted device architectures, the development of stable charge transport layers, and the integration of durable electrodes. By highlighting key advances over the past two years, we illustrate how strategic device engineering not only mitigates degradation but also preserves high performance, thereby helping to bridge the gap between laboratory achievements and commercial viability. Finally, we outline promising research directions aimed at further enhancing the stability of OSCs.