Improvement of TiO2/Se Heterojunction Characteristics for Highly Efficient Se Photovoltaic Devices

This paper reports a comparative study of anatase- and rutile-TiO2 thin films on TiO2/Se hetero junction photovoltaic cells. Anatase- and rutile-TiO2 thin films were deposited by intentional control of sputtering pressure and substrate temperature in reactive sputtering process. Se photovoltaic devices with rutile-TiO2 thin films exhibited higher short circuit current densities and photovoltaic conversion efficiencies than those of devices with anatase TiO2 layers. This result would attribute to suitable band alignment between rutile-TiO2 and Se layers. Conduction band alignment between Se and TiO2 layers is also discussed in connection with the measured optical bandgap energies and ionization energies. © 2022 The Institute of Electrical Engineers of Japan.