Electrodeposited chalcopyrite CuInGaSe2 absorbers for solar energy harvesting

Abstract

CuInGaSe2 (CIGS) based compound semiconductors are among the leading materials for photovoltaic applications. Pulsed current electrochemical deposition is employed in this study to fabricate CIGS films wherein deposition is carried out from an electrolyte consisting chlorides of copper, indium, gallium and selenous acid at a pH around 2.2. The process also uses trisodium citrate which plays the role of complexing agent and aids in narrowing the reduction potentials of elements thereby easing the optimization to obtain desired composition. The precursor films are annealed in Ar at 550 °C and are characterized comprehensively. Results unveil that CIGS films possess compact agglomerated particle like morphology with an average particle size of ≈500 nm, copper-poor stoichiometric composition, and tetragonal chalcopyrite structure devoid of any unwanted secondary phases. Optical studies yield the bandgap to be ≈1.2 eV. Photoelectrochemical performance ascertains the photoactivity of CIGS under illumination. The low-cost pulse electrodeposition for obtaining pure quality CIGS films, which is also scalable and can be a great choice for fabrication of economic solar cells.

Keywords

• Solar energy
• CuInGaSe2
• Electrodeposition
• Complexing agent
• Photoelectrochemistry