Hysteresis Effects in Photovoltaic Devices Based on a Two-Dimensional Molecular Ferroelectric

Narrow bandgap two-dimensional molecular ferroelectric materials have enormous potential in the field of optoelectronics, but excellent species are still scarce. (4-Iodobutylammonium)₂(methylammonium)₂Pb₃I₁₀ (IBMPI) has been demonstrated to be a low-bandgap two-dimensional biaxial mixed perovskite molecular ferroelectric. In this work, we used IBMPI as the light-absorbing layer to fabricate p-i-n structured photovoltaic devices. Under the irradiation of AM 1.5 G, the IBMPI-based solar devices exhibit significant photovoltaic effects (V_OC ≈ 0.78 V, J_SC ≈ 5.07 mA/cm²). In addition, by adjustment of the bias history, the intrinsic ferroelectric polarization and ion migration in IBMPI can also be used to adjust photovoltaic performance, especially the open-circuit voltage and fill factor. This work indicates that this two-dimensional molecular ferroelectric is a potential candidate material for preparing tunable photovoltaic devices.