Polarization-Enhanced Photovoltaic Effects in a High-Temperature Molecular Ferroelectric [C₆N₂H₁₈][SbI₅]-Based Solar Device

Molecular ferroelectrics with narrow bandgaps has great potential in the photoelectric field, but the outstanding species are still scarce. Herein, [C6N2H18][SbI5] has been demonstrated as a room-temperature (RT) molecular ferroelectric and applied to the organic–inorganic hybrid solar cells as the light-absorbing layer. The polar orthorhombic structure was solved by single-crystal XRD. The inherent RT ferroelectricity was revealed by hysteresis measurements with superior saturation polarization (Ps), remanent polarization (Pr), and coercive field (Ec) as 12.55 μC/cm2, 10.78 μC/cm2, and 0.33 kV/cm, respectively. The [C6N2H18][SbI5]-based solar device exhibits a significant photovoltaic (PV) effect under AM 1.5 G illumination with Voc ∼ 0.43 V, Jsc ∼ 35.17 μA/cm2, and a fast response time of ∼0.33 ms. A dramatical enhancement in PV performance has been achieved by turning the ferroelectric polarization, leading to the maximum Voc ∼ 0.75 V, Jsc ∼ 1.09 mA/cm2, and a power conversion efficiency (PCE) of 0.29%. This work offers a bright avenue for molecular ferroelectrics in optoelectronic devices.