Standard Si Photovoltaic Devices Improved by ZnO Film Obtained by Pulsed Laser Deposition

In recent years photovoltaic cells have been used increasingly, which is connected with growing energy demand, with exploitation of conventional energy sources, and with “green” tendency in the development of renewable sources of energy. Photovoltaic cell (PV) industry is now dominated by silicon technology due to its stability (average lifetime of silicon cells is estimated for 20 years), low emergency, ease of production, and no need for maintenance. The theoretical maximum of efficiency for these cells is 29%, whereas the commonly used cells have efficiency of about 20–21% for cells and 18–19% for modules with records of about 25.6% for cells and 23.8% for modules. One of the methods for increasing the PV efficiency is deposition of antireflection coating. In this work the zinc oxide thin films were deposited on standard silicon PV cells by pulsed laser deposition (PLD) method at different temperatures of silicon and ITO/glass substrates (TS = 25–300 °C) using second harmonic of YAG:Nd3+ laser. Photovoltaic properties of PV structures were determined by current-voltage characteristic analysis. The structural properties of zinc oxide films were analyzed by scanning electron microscope (SEM) technique. The structure of obtained ZnO layers was planar or columnar depending on substrate temperature. For structures with planar type of growth, the PV output efficiency decreased from 12% to 9%, while in the case of columnar type of growth, the output efficiency increased from 12% to 17%.