The high-efficiency (17.1%) WSe2photo-electrochemical solar cell

Abstract
WSe2 crystals (photo-electrodes) have been grown via a vapour transport technique, employing SeCl4 as transporter photo-electrochemical (PEC) solar cells with n-WSe2/I-, I2/Pt have been fabricated. In order to improve upon the efficiency, the effective WSe2 crystal surfaces have been etched in aqua-regia. The authors have obtained a high PEC conversion efficiency, up to 17.1%. This corresponds to the most efficient WSe2-based PEC solar cell reported so far. Evidence and arguments have been presented to show that the high efficiency ( approximately 17.1%) is achieved due to the combined effect of improved crystal quality, obtained through a SeCl4 transporter, and a decrease in the density of surface steps consequent to photo-etching.