Conformational Engineering Overcomes Multi-Mode Degradation in Perovskite Solar Cells
Perovskite solar cells (PSCs) have achieved certified efficiencies exceeding 27%, rivaling silicon-based technologies, yet their operational stability under real-world conditions remains a critical barrier to commercialization. Exposure to full-spectrum sunlight, particularly ultraviolet (UV) radiation, coupled with diurnal temperature fluctuations and ingress of moisture and oxygen, induces multi-mode degradation pathways, including lattice distortion, defect accumulation, and interfacial strain. Conventional stabilization strategies typically address single degradation routes and rely on static passivation or fixed strain compensation, failing to adapt to the dynamic stress fields arising from thermal expansion-contraction cycles at buried interfaces. Here, we highlight a recent breakthrough by Zhou et al. that introduces a stepwise conformational engineering strategy to design multifunctional molecules capable of simultaneous UV shielding, dynamic strain regulation, and defect passivation. Starting from 1,1-diphenylethylene (DPE), which exhibits intrinsic UV absorption, a flexible octyl alkyl chain is incorporated to yield 1-octyl-2-(1-phenylvinyl)benzene (OPVB). The conformational freedom of the alkyl chain enables reversible thermal expansion and contraction, allowing in situ modulation of interfacial stress. Further functionalization with hydroxyl and carbonyl groups produces diethylamino hydroxybenzoyl hexyl benzoate (DHHB), which integrates all three targeted properties. This molecular design addresses the bottleneck of multi-mode degradation by providing dynamic stress management, UV protection, and defect healing, thereby enhancing device stability and performance. The work establishes a new paradigm for fabricating stable PSCs under realistic operating conditions, with implications for accelerating industrial deployment.