Bioinspired Strain-Engineered Perovskite–Organic Tandem Solar Cells: Advances in Organic Semiconductors for Wearable Photovoltaics

Wearable and biointegrated electronics require lightweight, flexible, and highly efficient power sources capable of adapting to dynamic human motion. Perovskite–organic tandem solar cells (P-O TSCs) have recently emerged as a promising candidate for photovoltaic applications due to their tunable bandgaps, mechanical compliance, and high transparency. In addition to the conventional optimization of devices, the bioinspired strain-engineering paradigm offers a transformative pathway to enhance both efficiency and mechanical durability. The impetus for this research derives from natural architectures, including hierarchical tissues, nacre-like layered composites, and stretchable cellular frameworks. The integration of strain-adapted perovskite and organic semiconductor layers has been demonstrated to mitigate fracture, suppress ion migration, and stabilize interfacial energetics. This review synthesizes progress from 2001 to 2026, highlighting advances in lead-free and hybrid 2D/3D perovskites, narrow-bandgap organic absorbers, next-generation organic semiconductors, and flexible transparent electrodes. Particular emphasis is placed on bioinspired strain-engineering strategies such as hierarchical interlayers, island-bridge architectures, and serpentine interconnects, decoupling global deformation from local stress and preserving electronic functionality under repeated bending. The integration of these chemical, interfacial, and structural approaches enables PO-TSCs to achieve high efficiency alongside mechanical resilience. The final barriers to commercialization are outlined and include scalability, long-term stability under multistress environments, and eco-compatibility. The integration of biomimetic design principles with materials science and device engineering offers a framework for the development of sustainable, adaptive, and industrially viable tandem photovoltaics for the next generation of wearable and transparent energy-harvesting systems.