SERIES RESISTANCE IN N-MOSE2 (TMDC)-BASED PEC SOLAR-CELLS

Transition metal dichalcogenides (TMDCs) have been noticed as potential materials for the PEC solar cells because they are inherently stable against the electrolytic environment. Since MoSe2-a member of group VI TMDCs-possesses an optically matching band gap of around 1.4 eV, it holds relatively more promise as a better material for such devices. In this article, the authors report their investigations on PEC solar cells fabricated using n-MoSe2 crystals grown by a direct vapour transport technique. The photoconversion characteristics of n-MoSe2/I2/I-/pt PEC solar cells were investigated under polychromatic illumination from an incandescent lamp at various intensities. Since the series resistance of TMDC-based PEC solar cells is expected to be high, it may be one of the major parameters blocking the available power on photoconversion from such devices. Efforts have been made here to estimate its value. In addition, the effect of thermal treatment of the photoelectrode on the series resistance was also investigated. It has been found that the series resistance decreases from 4.01 K ohms to 1.93 K ohms on controlled thermal treatment of the photoelectrode. This is accompanied by a marked increase in the photoconversion efficiency (from 3% to around 12%). Thus, it can be concluded that the contribution of the series resistance in TMDC-based PEC solar cells is quite significant and can be reduced by giving controlled thermal treatment to the photoelectrodes.