Next-Generation Flexible PhotovoltaicsInterfacial Engineering, Stability Enhancements, And Advanced Nanocomposites In All-Perovskite Solar Cells

Abstract

Innovations in buried interfaces low temperature processing and solvent orthogonal recombination layers have brought flexible all-perovskite photovoltaics from proof-of-concept devices to mechanically robust modules with increasingly plausible efficiency-stability balance. Device records generally measure only one type of stress, such as tensile stress or only bending in radius, or only measure stress on a rigid substrate without accounting for polymer-substrate constraints. This review critically synthesizes the literature exploring key questions: What is the relationship between interfacial selectivity and adhesion? What is the relationship between strain transfer and fracture? What is the relationship between chemical changes under heat, light, bias, oxygen, and moisture and both interfacial selectivity and adhesion? This article introduces a new framework, Interface–Mechanics–Chemistry Coupling (IMCC), which focuses on explicit linkage among interfacial selectivity and adhesion, strain transfer and fracture and chemical changes under heat, light, bias, oxygen and moisture. We introduce flexible all-perovskite tandems and expand on their device physics and architectures, highlighting the key differences with flexible single-junction, rigid all-perovskite and perovskite/silicon devices. Although the flexibility of all-perovskite tandems is proven, processing-aware recombination layers serve as both electrical contacts and barriers, molecule-bridged electrical contacts can enhance adhesion and reduce recombination, scalable in situ additive/gas-quench coating can offer large-area wide-bandgap films and durable modules, and nanoscale control of PEDOT:PSS phase distribution can transform wettability, interfacial dipoles and extraction in the narrow-bandgap subcells. Flexible single-junction studies provide fracture-mechanics perspective, and multifunctional nanocomposite studies provide insight into dissipation and self-healing, which are not yet demonstrated to be effective in flexible tandems. In the IMCC framework study the interplay of band alignment, ion migration and electronic axis (interfacial dipoles) with neutral axis (placement), fracture energy of interface (IF), and cyclic fatigue/fracture (MF) (mechanical axis) and Sn(II) redox (chemical axis) and halide segregation and moisture/oxygen ingress. We recognize gaps that are testable: lack of harmonized multi-stressor mechanical standards, lack of operando access to buried interfaces under deformation and lack of integrated control of the Sn-rich redox and wide-bandgap phase stability through low-temperature, scalable processing. Finally, we finish by discussing the translation from a coupon cell to roll-to-roll module and sustainability, where all the considerations of lead containment, recycle and choice of solvents are treated as part of the design process, not as a last resort.