High-Sensitive Interfacial Charge Response in 3D/2D Heterostructure-Based Normal and Inverted Perovskite Solar Cells

Effective interfacial charge extraction and suppressed defect-assisted recombination improve the transient response and prolong the photogenerated carrier lifetime, two decisive factors governing the efficiency of perovskite solar cells (PSCs). In this study, transient absorption spectroscopy is employed to elucidate the impact of the 3D/2D heterostructure on carrier transport and recombination dynamics in both normal and inverted devices. By passivating the 3D perovskite with a phase-pure 2D perovskite layer, the defect-assisted recombination lifetime is successfully increased from 90.7 to 240 ns. Meanwhile, a sensitive transient response with faster interfacial charge transfer lifetime ∼174 ps is achieved in phase-pure 3D/2D heterostructure-based normal PSCs compared to the bare 3D perovskite (∼220 ps). On the other hand, to overcome the deteriorative interfacial carrier behavior caused by the mismatched energy level of 3D/2D heterostructure in inverted PSCs, a 4-methoxyphenylphosphonic acid (MPA)-modified dipole layer is introduced to regulate energetics. This modification further suppresses defect-assisted recombination with a prolonged lifetime of 252 ns. Simultaneously, a highly sensitive interfacial charge transfer lifetime of 169 ps is successfully realized in 3D/MPA/2D-based inverted PSCs. Furthermore, transient absorption microscopy reveals the highest carrier mobility (12.40 cm²V^–1s^–1) in 3D/MPA/2D architecture, facilitating charge carriers to diffuse more rapidly to the interface. Finally, the fabricated 3D/MPA/2D inverted PSC achieves the champion power conversion efficiency of 24.82% compared to the 3D perovskite device of 21.39%. Our work has completely revealed the ultrafast spatiotemporal dynamics of photogenerated carriers in 3D/2D heterostructures, providing profound insights for the design of high-performance photovoltaic devices.