Photovoltaic performance of p-AgGaSe2/n-CdS thin film heterojunction

The optimized deposition conditions for obtaining single-phase polycrystalline p-AgGaSe₂ films are described, and preliminary results on the performance of p-AgGaSe₂/n-CdS thin-film heterojunctions are given. Polycrystalline thin-film p-AgGaSe ₂/n-CdS (1.5 at.% In-doped) heterojunctions were fabricated by flash evaporation of AgGaSe₂ onto CdS film. From the dark current-voltage characteristics at 303 K, the diode quality factor and saturation current density were found to be 1.6 and 3×10^-7 A/cm², respectively. The dark current-voltage characteristics at different temperatures indicated that the junction current was controlled by recombination in the depletion region. The built-in voltage and depletion-layer width were 0.90 V and 0.7 μm, respectively. The acceptor state density was 3×10¹⁶ cm ^-3, and the device shows an interface state density of 5×10¹² cm^-2. As-deposited AgGaSe₂-CdS heterojunction cells showed an electrical conversion efficiency of 4.5% for an active area of 1 cm². The quantum efficiency of these cells was less than 70%