Two-Dimensional WSe₂/MoS₂ p–n Heterojunction-Based Transparent Photovoltaic Cell and Its Performance Enhancement by Fluoropolymer Passivation

As a means to overcome the limitation of installation space and to promote the utilization of the solar cell in various applications, a transparent thin-film solar cell has been studied by many researchers. To achieve a transparent solar cell, the choice of materials which are transparent enough and showing the photovoltaic property at the same time is the key. Here, we suggest a two-dimensional (2D) p–n heterojunction of WSe2/MoS2 and an indium tin oxide electrode to fabricate a transparent thin-film photovoltaic cell. Because of advantages that 2D materials possess, a highly transparent (∼80%) solar cell with considerable efficiency was achieved. Furthermore, by introducing a transparent passivation layer composed of a fluoropolymer, the photovoltaic performance was much improved. With the passivation layer, our WSe2/MoS2 transparent photovoltaic cell reached an efficiency of ∼10%. A comparison of photovoltaic parameters before and after applying passivation and analysis on the origin of such differences are also discussed. To the best of our knowledge, this is the first report to fabricate a 2D material-based fully transparent photovoltaic device. Our result exhibits a great potential of the van der Waals p–n heterojunction of 2D semiconductors to be utilized for an active layer of a highly transparent and lightweight thin-film solar cell.