Fully solution processed all inorganic nanocrystal solar cells

Abstract

The effects of solution (sol) processed contacts of indium tin oxide (ITO-sol) and gold (Au-sol) on solar cells are tested. When combined with solution processed active layers of CdTe/CdSe, all-inorganic fully solution processed solar cells are produced on non-conductive glass substrates. Under AM 1.5G illumination, open circuit voltages (V_oc), short circuit currents (J_sc) and efficiencies (η) of solar cells processed with evaporated Au and commercial ITO were found to be (V_oc = 0.56 ± 0.04 V, J_sc = 17.2 ± 2.2 mA cm⁻², η = 3.8 ± 0.4%), with Au-sol replacement (V_oc = 0.54 ± 0.03 V, J_sc = 12.6 ± 1.0 mA cm⁻², η = 2.0 ± 0.1%), with ITO-sol (V_oc = 0.38 ± 0.04 V, J_sc = 12.3 ± 0.8 mA cm⁻², η = 1.3 ± 0.2%), and with each layer solution processed (V_oc = 0.49 ± 0.01 V, J_sc = 10.0 ± 1.5 mA cm⁻², η = 1.5 ± 0.2%) with the champion fully-solution processed all-inorganic device showing η = 1.7%. Layers and devices were characterized with UV/Vis spectroscopy, optical profilometry, XRD, XPS and SEM. The results indicate that the reduced performance of the all-solution devices results primarily from increased roughness of the Au film and decreased conductivity of the ITO layer.