Simulation and performance analysis of superstrate Cu(In,Ga)Se<SUB align="right">2 solar cells using nanostructured Zn<SUB align="right">1−xV<SUB align="right">xO thin films

Abstract

In this paper, we describe in the first step the structural, electrical and optical properties of the nanostructured Zn 1– x V x O thin films deposited on glass substrates by rf-magnetron sputtering using aerogel nanoparticles synthesised by the sol–gel method. The best properties, satisfying the role of window and buffer layers, were achieved, respectively, for the films of Zn 0.99 V 0.01 O elaborated at room temperature and Zn 0.80 V 0.20 O at 200ºC. In the second step, the nanostructured Zn 0.99 V 0.01 O and Zn 0.80 V 0.20 O layers are, respectively, proposed as alternative to the traditional (ITO) window and (CdS) buffer layers and tested numerically in Cu(In,Ga)Se 2 (CIGS) solar cell using one-dimensional AMPS-1D device simulator. The influence of physical and geometrical parameters of the p -type CIGS absorber layer on the performance of the superstrate SLG/(n+)Zn 0.99 V 0.01 O/(n)Zn 0.80 V 0.20 O/(p)Cu(In,Ga)Se 2 /Mo solar cell was investigated. The calculations assume fixed Zn 1– x V x O input parameters. The carrier concentration and thickness of the absorber layer were found to be a key factor, affecting the solar cell performance. On the basis of the simulation results, a short-circuit current density of about 33 mA/cm 2 has been obtained for 4 µm-CIGS solar cell using n -type Zn 0.80 V 0.20 O buffer layer for 100 nm thick. It is also found that a conversion efficiency of more than 19% AM 1.5 G could be expected for more than 3 µm absorber thickness and acceptor concentration varying between 2 × 10 16 and 10 17 cm –3 . From the results obtained, we suggest the use of Zn 0.80 V 0.20 O and Zn 0.99 V 0.01 O as a buffer and window layers, respectively, to achieve high-efficiency CIGS solar cells with better photovoltaic parameters.