Photovoltaic Characteristics of GaSe/MoSe₂ Heterojunction Devices

The two-dimensional materials have the thickness of an atomic layer level and are expected as alternative materials for future electronics and optoelectronics due to their specific properties. Especially recently, transition metal monochalcogenides and dichalcogenides have attracted attention. Since these materials have a band gap unlike graphene and exhibit a semiconductor property even in a single layer, application to a new flexible optoelectronics is expected. In this study, the photovoltaic characteristics of a GaSe/MoSe₂ heterojunction device using two-dimensional semiconductors, p-type GaSe and n-type MoSe₂, were investigated. The heterojunction device was prepared by transferring GaSe and MoSe₂ onto the substrate which the titanium electrodes were fabricated through a mechanical peeling method. The current-voltage characteristics of the GaSe/MoSe₂ heterojunction device were measured in a dark condition and under light irradiation using a solar simulator. The irradiation light intensity was changed from 0.5 to 1.5 sun. It was found that when the illuminance was increased in this illuminance range, both the short-circuit current and the open-circuit voltage increased. The open-circuit voltage and the energy conversion efficiency were 0.41 V and 0.46% under 1.5 sun condition, respectively.