Bi2MoO6 photovoltaic effect of thin films based on composition distribution and structural design

Photovoltaic devices based on single-film architectures, often realized in ferroelectric thin films, are valued for their structural simplicity and low fabrication costs. Nonetheless, their practical use is constrained by wide bandgaps and limited photoelectric responsivity. This study demonstrates a robust photovoltaic effect in paraelectric Bi 2 MoO 6 thin films fabricated through the sol-gel technique. By introducing an excess of bismuth into the precursor solution, the Bi content within the films is effectively tuned, revealing a strong dependence of the photovoltaic behavior on Bi concentration. The internal electric field driving the photovoltaic response is attributed to a compositional gradient of Bi ions across the film. Under 365 nm illumination, the optimized Bi 2 MoO 6 film exhibits notable photovoltaic performance, including a photoelectric responsivity of 31.25 mA/W, a short-circuit current density of 0.25 mA/cm 2 , and an open-circuit voltage of 0.36 V. This study not only expands the application of Bi 2 MoO 6 in photovoltaic field but also proposes an approach to design the photovoltaic effect in paraelectric oxides.