Photovoltaic effect in paraelectric BiVO4 film

Photovoltaic effects of single-layer films, with simple structure and low cost, are generally found in ferroelectric films, but their applications in solar cell are restricted by the large band gap of ferroelectrics. Here, we demonstrate a large photovoltaic effect can be obtained in paraelectric single-layer BiVO4 (BVO) film based on the gradient distribution of charges. The circuit current density (JSC) and open circuit voltage (VOC) of the BVO film with best performance are 1.63 mA/cm2 and 0.38 V, respectively. The JSC of BVO film kept 86% of the maximum value after continuous operation for 16 h. The high thermal stability of BVO is proved by long time operation and stable photovoltaic performance at high temperature. This work not only proposes a novel built-in electric field mechanism, but also indicates that the single-layer paraelectrics can be used as the next generation photovoltaic materials.