ZnO nanowire based CIGS solar cell and its efficiency enhancement by the piezo-phototronic effect

• Published in: Nano energy 2018-07, Vol.49, p.508-514
• Main Authors: Qiao, Shuang, Liu, Jihong, Fu, Guangsheng, Ren, Kailiang, Li, Zhiqiang, Wang, Shufang, Pan, Caofeng
• Format: Article
• Language: English
• Subjects: CIGS heterostructure; Piezo-phototronic effect; Solar cells; ZnO nanowire
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2018.04.070

Cu(In,Ga)Se2(CIGS)-based heterostructures have been thought to be one of the most prospective thin film solar cells. However, considering cost competitiveness, researchers are still seeking for new methods to improve the power conversion efficiency (PCE). In this work, the ZnO nanowires are first introduced into the CIGS-based solar cells to substitute the ZnO film for well developing the piezoelectric effect. Interestingly, the solar cells exhibit very good photovoltaic performances with PCE of 9.83% for rigid device and 5.43% for flexible device, the PCE of which is even larger than that of the corresponding ZnO film CIGS devices. Moreover, by exerting piezo-phototronic effect of the ZnO nanowires, the PCE of the rigid device is modulated from 9.83% to 11.40% with vertical pressure increasing from 0 to 2 MPa, and the PCE of the flexible device improves from 4.82% to 5.96% with external strain changing from a 0.74% tensile strain to a −0.74% compressive strain. This study demonstrates that introducing ZnO nanowires as well as the associated piezo-phototronic effect provides an ideal approach for improving the performances of CIGS-based solar cells. The ZnO nanowires are introduced into the CIGS solar cells on both rigid and flexible substrates. The ZnO nanowire CIGS solar cells still exhibit very good photovoltaic performances. More importantly, the PCE of rigid device can be modulated from 9.83% to 11.40% under external pressures, and the PCE of flexible device increases from 4.82% to 5.96% with adding external strains. [Display omitted] •ZnO nanowires are first introduced in the CIGS-based solar cell.•Improved performances of the CIGS-based solar cell by the piezo-phototronic effect.•The efficiency is enhanced by 15.9% for rigid CIGS solar cell under vertical pressure.•The efficiency is improved by 23.7% for flexible CIGS solar cell under compressive strain.