OPTICAL AND PHOTOVOLTAIC PROPERTIES OF ZnS NANOCRYSTALS FABRICATED ON Al:ZnO FILMS USING SILAR TECHNIQUE

摘要

Hybrid solar cells with ITO/AZO/ZnS/P3HT/PCBM/Ag structure were fabricated, so that in the synthesis of ZnS layer, successive ion layer absorption and reaction (SILAR) technique was used. At first, the Al doped ZnO (AZO) layers with different molar concentration of Al were deposited on ITO-glass substrates and the optimum concentration was determined to produce the maximum power conversion efficiency. The ZnS layer with different SILAR cycles was then grown on ITO/AZO to fabricate the high efficient solar cell. X-ray diffraction analysis confirmed the formation of pure, nanocrystalline and cubic structure of ZnS. Optical measurements showed that band gap of ZnS quantum dots varies in a narrow range 3.8-4.0 eV, depending on the number of SILAR cycles. The effect of number of cycles on the solar cell performance was investigated. The photovoltaic properties of fabricated cells under the illumination of one sun (AM 1.5,100 mW/cm~2) have been examined. The results indicated that changing the number of SILAR cycles improves the performances of the fabricated photovoltaic cells; a high efficiency of 3.25% was observed at number of cycles 6.