One-step electrodeposition of CuAlGaSe2 thin films using triethanolamine as a complexing agent

Abstract CuAlGaSe2 thin films were obtained by one-step electrodeposition in an aqueous medium containing triethanolamine (TEA) as complexing agent, a platinum wire was used as counter electrode and a SnO2:F/CdS substrate as working electrode. The influence of TEA on the reduction potential of species (Cu2+, Al3+, Ga3+ and H2SeO3) involved in the co-electrodeposition of quaternary material was investigated. The cyclic voltammetry study was carried out in the Cu-TEA, Cu-Al-TEA, Cu-AI-Ga-TEA and Cu-Al-Ga-Se-TEA systems and scans revealed the formation mechanism of quaternary CuAlGaSe2. The formation of the quaternary compound CuAlGaSe2 could involve two possible routes: Al3+ and Ga3+ ions induced reduction by Cu3Se2, leading to the formation of CuAlSe2 and CuGaSe2; another is that the Al3+ and Ga3+ may react with H2Se, which are incorporated to more stable species CuAlSe2 and CuGaSe2, respectively. The structural characterization confirmed the formation of CuAlGaSe2. The band gap energy was tuned from 1.64 to 2.28 eV by changing Al/Ga content and annealing temperature.