Spray pyrolysis of semi-transparent backwall superstrate CuIn(S,Se)2 solar cells

We explored the feasibility of depositing CuIn(S,Se)₂ (CIS) absorbers using a recently developed hydrazine-based spray pyrolysis method in the backwall superstrate configuration. The devices were fabricated in a novel configuration consisting of a solution-processed CIS/CdS p-n junction sandwiched between two transparent conducting layers and photovoltaic responses was demonstrated with illumination through either side of the device. The structural, compositional, and electrical properties of the devices were investigated. The current voltage characteristics and quantum efficiency of the backwall superstrate and conventional substrate devices were studied. The performance of the backwall superstrate devices was less than that of the control devices due to the relatively thick absorber thickness and high sheet resistance of the transparent back contact. Further improvement in the crystal quality and stoichiometry of CIS deposition should lead to high efficiency devices with thinner and better quality absorbers.