Electrodeposition of single phase CuInSe2 for solar energy harvesting: Role of different acidic additives

Abstract

Single phase CuInSe2 (CIS) absorber material is required for producing high quality thin film solar cells, as the presence of impurity Cu2?xSe leads to short circuit of the cells. Traditionally, the deposition of single phase CIS requires the use of a suitable chelating agent to shift the Cu2+/Cu redox couple towards the redox potential of the In3+/In couple, and also an acid to adjust the pH of deposition bath around 2. We propose a novel idea of using suitable acids that could concurrently also serve as the chelating agent. Oxalic acid, acetic acid and hydrochloric acid were investigated on their ability to serve this dual function. We found that oxalic acid is the most promising additive because the CIS film deposited was densest and yielded the highest photocurrent.