Multiferroic Bi₂FeCrO₆ based p–i–n heterojunction photovoltaic devices

Photovoltaic devices made of ferroelectric films are being widely studied, due to their efficient charge separation driven by the internal polarization as well as above-bandgap generated photovoltages. These features may enable power conversion efficiencies (PCE) exceeding the Shockley–Queisser limit, which characterizes conventional semiconductor-based solar cells. However, improving the PCE of such devices is still a challenge, mainly due to the weak charge transport and collection induced by the recombination of photocarriers. Here, we fabricated p–i–n heterojunction devices based on double-perovskite multiferroic Bi₂FeCrO₆ thin films. The latter act as intrinsic absorbers, sandwiched between hole- and electron-transporting layers, a p-type NiO and an n-type Nb-doped SrTiO₃ semiconductor, respectively. Under 1 sun illumination, the optimized p–i–n device yields an open-circuit voltage of 0.53 V and a short-circuit current density of 8.0 mA cm⁻², leading to a PCE of ca. 2.0%, a four-fold enhancement compared to that of the i–n device architecture.