One-year ambient stability: Nanostructured mixed-dimensional perovskite solar cells with enhanced performance

Although three-dimensional (3D) perovskite solar cells (PSCs) demonstrate high power conversion efficiency (PCE), their instability under humidity, oxygen, and ultraviolet (UV) irradiation limits their practical applications. Lower-dimensional perovskites are much more stable under environmental stresses but are invariably poor photovoltaic performers. To simultaneously enhance both PCE and stability, we engineered mixed-dimensional (MD) PSCs by incorporating p -phenylenediaminium (PDA) into a (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 3D perovskite matrix. The nanostructured MD perovskite films were fabricated via a sequential deposition method under ambient conditions, enabling controlled dimensionality through optimized dipping duration. The MD30 devices, processed with a 30-s dipping duration, achieved a remarkable PCE of 20.28 %, attributed to optimized crystal orientation, improved surface morphology, enhanced charge transport, and suppressed carrier recombination. Notably, the MD30 devices exhibited exceptional stability under harsh environmental conditions. When exposed to 85 % relative humidity (RH) for 300 h, unsealed devices retained 92.4 % of their initial PCE. Similarly, after 300 h of thermal aging at 85 °C, the PCE remained at 96.4 % of its original value. Furthermore, the devices maintained 89.7 % of their initial efficiency after one year of storage under ambient conditions (RH ≈ 38 %, T ≈ 25 °C) without encapsulation. This work presents a strategic design approach for developing next-generation PSCs with high efficiency and long-term stability. • Highly stable nanostructured mixed-dimensional perovskite solar cell is fabricated via sequential deposition method. • The dipping duration significantly affects the n value of mixed-dimensional perovskite layer. • The use of nanostructing strategy leads to the efficiency enhancement from 15.20 % to 20.28 %. • Improvement of stability is achieved with retaining 89.7 % of initial efficiency after one year.