CuInSe ₂ (CIS) thin film solar cells by electrostatic spray deposition

In this paper, we demonstrate, for the first time, the manufacture of a CuInSe ₂ thin film whose absorber layer is coated using an electrostatic spray deposition (ESD) technique; its complete transformation into a working device with measured conversion efficiency is presented. ESD is superior to pneumatic spraying because it produces nano-scaled, self-dispersive (non-agglomerating), highly wettable (electrowetting) and adhesive droplets to yield a uniform coating on a substrate. Furthermore, ESDs extremely low material consumption rate holds promises for practical use in the solar cell industry. Copper and indium salts are added to various solvents, which are electrostatically sprayed onto a molybdenum-coated soda-lime glass substrate. The effect of substrate temperature on the thin film characteristics is examined. Our cell is completed by adding CdS and ZnO layers onto the CuInSe ₂ absorber layer. Light illuminated current-density voltage (J-V) characteristics demonstrate a power conversion efficiency of η = 1.75% ± 0.09 with an open-circuit voltage of V _OC = 0.23 V, a short-circuit current density of J _SC = 21.72 mA/cm ², and fill factor of FF = 0.34.