Ultrathin emerging photovoltaics for future wearable and soft robot applications

Abstract

Fabricating emerging photovoltaics on ultrathin polymer substrates (~1µm) significantly minimizes areal mass and flexural rigidity, unlocking exceptional power-per-weight ratios exceeding 40Wg⁻¹ and self-adhesive conformability to dynamic biological surfaces. Recent progress has steadily closed the power conversion efficiency (PCE) gap between rigid, flexible, and ultrathin organic photovoltaics, achieving comparable performance across substrate form factors. However, the lack of standardized mechanical testing methodologies has long hindered equitable comparisons of device durability. Here, we review the mechanical scaling principles of ultrathin photovoltaics and discuss the international consensus bending protocol (1% strain over 1,000 cycles) alongside the flexible photovoltaic fatigue factor (F). Furthermore, we address large-area manufacturing via scalable, low-temperature solution coating. We highlight a fluid-dynamic control framework in meniscus-guided bar coating of triple-cation perovskites at 100°C, where Couette–Marangoni convective circulation suppresses local supersaturation to yield giant crystal domains with minimized hysteresis. Finally, we demonstrate a vacuum-free universal trilayer platform utilizing ambient-sprayed liquid-metal electrodes, enabling monolithic integration of solar modules with light emitters and photodetectors for continuous, self-powered cardiovascular health monitoring. These advances establish a practical foundation for durable, high-throughput, and imperceptible power solutions in future wearable devices and autonomous soft robotics.