Hybrid CuInS2/polypyrrole and CuInS2/poly(3,4-ethylenedioxythiophene) photovoltaic structures

Photovoltaic (PV) structures based on inorganic photoabsorber CuInS2 (CIS) in combination with conductive polymers polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared using electrodeposition and spin-casting techniques. The conductive polymer layer is considered as the p-type buffer layer and window layer on CIS absorber layer in the cell structure. The CIS thin films were fabricated using a non-vacuum CISCuT technique on Cu tape substrate. All obtained polycrystalline CIS films were etched in 10% KCN and annealed in vacuum to improve the crystalline structure. PPy films doped with β-naphthalene sodium sulfonate were electrodeposited under white light illumination onto the pretreated CIS films. Thin PEDOT films doped with polystyrenesulfonate (PSS) were deposited onto the CIS films from an aqueous dispersion of PEDOT/PSS mixed with N-methylpyrrolidone, isopropanol, glycerin and epoxysilane additives using the spin-casting technique. In order to prepare stable PPy and PEDOT films with a good adherence to the surface of inorganic semiconductor CIS, the appropriate parameters of electrodeposition and spin-coating were selected experimentally. Significant photovoltage and photocurrent of the fabricated complete structures have been observed under standard white light illumination.