A Buried Interface Fastening Approach for Efficient and Flexible Perovskite Photovoltaics

Abstract Organic–inorganic halide perovskite solar cells (PSCs) have demonstrated a promising advancement in flexible and lightweight photovoltaics. Nevertheless, achieving their large‐area printed fabrication remains challenging, especially the issue of defect enrichment at the buried interfaces, which is crucial for efficient carrier transport. Herein, an interfacial fastening strategy is designed to enhance the performance and stability of PSCs, involving the introduction of hexamethylene diisocyanate (HDI) into the perovskite precursor and ethylene glycol (EG) on electron transport layers. The in situ reaction between HDI and EG during film formation can inhibit the formation of complex intermediate phases during precursor deposition, thus achieving the uniform colloidal distribution, mitigating the gradient residual stress mismatch of perovskite films, and enhancing the buried interfacial contact. The resulting rigid, flexible PSCs and modules (25 cm 2 ) achieve PCEs of 26.04%, 24.16%, and 20.40%, respectively, and encapsulated devices can retain over 80% efficiencies after storage for 6380 h. This work provides a potential to simultaneously optimize the contact quality at the buried interface and the crystallization quality of perovskites, which aligns with the requirements for large‐area, high‐quality, and homogeneous deposition of perovskite photovoltaics and facilitates the advancement of their printing manufacturing and commercialization transition.