Synthesis of CuInSe2 thin films on flexible Ti foils via the hydrothermally-assisted chemical bath deposition process at low temperatures

Single phased copper indium diselenide (CuInSe2) films have been successfully prepared on titanium substrates directly by adopting a hydrothermally-assisted chemical bath deposition technique. CuInSe2 films belong to the chalcopyrite structure were uniformly prepared at various penetration depths. The synthesis temperature of the monophasic CuInSe2 films was decreased to 180 °C without the selenization process. The required temperature for preparing single phased CuInSe2 films was remarkably lower than the temperatures used in conventional vacuum and non-vacuum processes. During the hydrothermal reaction, highly reactive selenium ions reacted with copper and indium ions directly to produce CuInSe2 films on the substrates without any high-temperature treatment, leading to the decrease in reaction temperatures appreciably. The increase in the hydrothermal temperatures significantly improved the crystallinity and enlarged the particle sizes of CuInSe2 films. This developed process can be effectively applied for the preparation of CuInSe2 films on flexible substrates at low temperatures.