Photoelectrochemistry of Cu(In,Ga)Se2 thin-films fabricated by sequential pulsed electrodeposition

A novel approach for the fabrication of compact stoichiometric copper indium gallium selenium (CIGS) thin-films is reported. It uses a solution of CuCl2, GaCl3 and H2SeO3, pH adjusted with HCl with LiCl as additive employing a high purity graphite plate anode and Mo sputtered glass cathode during a simplified sequential pulsed current electrodeposition which avoids impurities from the use of a reference electrode during deposition and a separate selenization step. A Cu-Ga-Se film is optimally deposited by optimizing the deposition voltage, followed by deposition of In from InCl3 solution, and then annealing of the Cu-Ga-Se/In thin-film in an Argon atmosphere at 550 degrees C. A single phase chalcopyrite CIGS forms with a compact morphology and well-controlled composition of individual elements. The flat-band potential and carrier density of CIGS thin-films are -0.15 V and 2.6 x 10(16) cm(-3), respectively, as determined by Mott-Schottky studies. The photoelectrochemical performance of CIGS films shows a photocurrent density of -0.8 mA cm(-2) at -0.4 V vs. SCE, an eight fold increment compared to our previous reported value. This simplified preparation using pulse plating gives superior quality CIGS films which are promising for application in thin-film solar cells and photoelectrochemical cells. (C) 2014 Elsevier B.V. All rights reserved.