Increasing surface band gap of Cu(In,Ga)Se_2 thin films by post depositing an In-Ga-Se thin layer

Abstract

We have developed a simple approach to fabricate wide band gap surface layer for Cu(In,Ga)Se2 (CIGS) thin film. The Cu depleted surface layer was reconstructed by an In-Ga-Se post deposition treatment at different temperatures, which was monitored by a light controlling method. A desirable Cu concentration in surface layer has been achieved after depositing a 80 nm thick In-Ga-Se layer at 400°C and the corresponding device performance is remarkably improved compared with device without surface modification. Additionally, the excess Cu(2-x)Se phase on the surface could also be eliminated by this method in case of high Cu/(In+Ga).

New Solution-Processed Surface Treatment to Improve the Photovoltaic Properties of Electrodeposited Cu(In,Ga)Se2 (CIGSe) Solar Cells

“…The Ga-poor (or In-rich) topmost surface led to a reduction in the surface band gap, which deteriorated the open-circuit voltage. To improve the surface band gap, Tan et al supplemented In–Ga–Se through evaporation and concluded that the device performance was remarkably improved. Choubrac et al used Ga–PDT treatment to supplement the surface Ga content and passive grain boundaries and CIGSe/CdS interfaces, which led to a reduction in the V OC deficit.…”

Photovoltaic electrical properties of aqueous grown ZnO antireflective nanostructure on Cu(In,Ga)Se_2 thin film solar cells

“…Thin film solar cells are one of the attractive technologies for generating electrical energy by absorbing photons from sunlight. Among all technologies, polycrystalline Cu(In,Ga)Se 2 (CIGSe) thin films are considered to be a highly promising candidate for its high absorption coefficient, stability, and suitable band gap [1][2][3]. To realize a mass-producible energy application, the selenization process is a cost-effective and large-scale method to fabricate CIGSe thin films [4,5].…”