Fabrication of Zn-doped Cu(In,Ga)Se2 thin film solar cells prepared by Zn diffusion from the gas phase using dimethylzinc

Cu(In,Ga)Se2 (CIGS) solar cells were fabricated by thermal diffusion of Zn into p -type CIGS films using dimethylzinc [(CH3)2Zn: DMZn] vapor, in order to form CIGS pn -homojunction. This method requires no additional processing equipment, because diffusion can be carried out subsequent to the CIGS growth. The average conversion efficiency of the CIGS solar cells consisting of n -type MgZnO transparent conducting oxide (TCO) film and n -CIGS:Zn/p -CIGS structure (4%) was improved by a factor of two in comparison with the case for undoped CIGS absorbing layer (2%). The appropriate flow time of DMZn was 3 s, from which the diffusion depth is estimated as about 150 nm. The method is highly advantageous for development of low-cost solar modules. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)