Enhanced Bulk Photovoltaics in Polar 2D Hybrid Perovskite via Pressure‐Strengthened Organic‐Inorganic Interactions

ABSTRACT The development of bulk photovoltaic effect (BPVE) in polar two‐dimensional (2D) organic‐inorganic hybrid perovskites (OIHPs) is currently impeded by an insufficient understanding of the microscopic mechanisms linking organic‐inorganic interactions to photovoltaic output. Here, we utilize pressure as an effective thermodynamic probe to decouple these interactions in BDA(EA) 2 Pb 3 Br 10 (BDA is 1,4‐butanediammonium, EA is ethylammonium), achieving the first pressure‐engineered synergistic enhancement of short‐circuit current ( I SC ) and open‐circuit voltage ( V OC ). Comprehensive in situ characterizations reveal that pressure‐strengthened N─H···Br hydrogen bonding induces cooperative organic cation ordering and inorganic octahedral distortion. This structural synergy amplifies spontaneous polarization, resulting in a 530‐fold increase in BPVE efficiency to 0.18% at 1.5 GPa, a value surpassing all previously reported OIHPs. Moreover, the enhanced organic‐inorganic interaction stabilizes the ferroelectric state, elevating the Curie temperature to 433 K. These results elucidate the microscopic mechanism underlying BPVE enhancement in 2D OIHP ferroelectrics and establish pressure modulation as an effective strategy for mechanistic studies and photovoltaic optimization.