Unveiling the potential of flexible perovskite photovoltaics: From lab to fab

Flexible perovskite-based single-junction and tandem solar cells have achieved power conversion efficiencies (PCEs) exceeding 25% and 29%, respectively, and are regarded as ideal for portable and wearable optoelectronic devices, including building-integrated photovoltaic (BIPVs) applications, compared to other thin-film technologies and mainstream silicon. This is because perovskite films can be prepared using a low-temperature process and solution-based roll-to-roll fabrication with a superior power-to-weight ratio and high cost-effectiveness. Despite these advancements, the commercialization of f-PSCs remains constrained by several challenges associated with each sandwiched layer stacked in the device configuration, including the perovskite active layer, charge-transport layers (CTLs), flexible substrates, and electrodes. The delicate crystallization of perovskites on flexible substrates typically results in inhomogeneous nucleation and unwanted defect formation in perovskite films. Furthermore, the polycrystalline nature of perovskite films with numerous grain boundaries induces degradation sites and increases the susceptibility to mechanical fracture. Furthermore, CTLs at perovskite film interfaces encounter challenges such as weak adhesion, chemical instability, energetic alignment mismatches, and residual stress or strain. In addition, the top and bottom electrodes, including flexible substrates, remain susceptible to cracking and delamination under mechanical stress and real-world operating conditions. Consequently, f-PSCs exhibit fragility, reduced operational stability, and lower PCE than their rigid counterparts. These limitations present significant barriers to the industrial-scale production and commercialization of f-PSCs. In this review, we comprehensively discuss the existing challenges and progress regarding the material design of flexible devices based on the state-of-the-art results of single- and multijunction-based flexible perovskite devices. This involves flexible substrates and transparent electrodes, perovskite crystallization growth at low temperatures, synthesis of suitable CTLs, and interface passivation engineering to enhance performance and mechanical stability. Furthermore, we discuss large-scale production techniques, future prospects of flexible perovskite modules and encapsulation design, and the existing market potential to highlight the potential of f-PSCs for wearable and self-powered electronic devices in modern energy-harvesting technology. Finally, we also highlight the flexible perovskite recycling strategies prior to commercialization and emphasize a low carbon footprint and minimal environmental impact.