Development of reflective back contacts for high-efficiency ultrathin Cu(In,Ga)Se2 solar cells

THIN SOLID FILMS

卷:672

Article; Proceedings Paper

Gouillart, Louis^1,3  Cattoni, Andrea¹  Goffard, Julie¹  Donsanti, Frederique²  Patriarche, Gilles¹  Jubault, Marie²  Naghavi, Negar³  Collin, Stephane¹ 

[1] Univ Paris Saclay, Univ Paris Sud, CNRS, Ctr Nanosci & Nanotechnol C2N, F-91120 Palaiseau, France

[2] IPVF, EDF R&D, 30 Route Dept 128, F-91120 Palaiseau, France

[3] IPVF, CNRS, UMR 9006, 30 Route Dept 128, F-91120 Palaiseau, France

关键词: Solar cells;    Copper indium gallium selenide;    Ultrathin films;    Transparent back contact;    Reflective back contact;    Nanostructured back mirror;   

DOI  :  10.1016/j.tsf.2018.12.041

来源: Elsevier

【 摘 要 】

Because of poor light absorption, Cu(In,Ga)Se-2-based (CIGS) solar cells with an ultrathin absorber layer (< 500 nm) require the development of reflective back contacts. To enhance rear reflectance in CIGS ultrathin devices, we investigate novel back contact architectures based on a silver metallic mirror covered with a thin layer of In2O3:Sn (ITO), which is fully compatible with nanopatterning for further light trapping improvements. First, numerical electromagnetic simulations of complete solar cells have been performed for a 490 nm thick CIGS absorber with various back contacts. We predict a short-circuit current density of J(SC) = 34.0 mA/cm(2) for a 490 nm thick CIGS absorber with a silver nanostructured mirror. Second, we have fabricated and characterized 490 nm thick CIGS solar cells with transparent back contacts made of ITO, and reflective back contacts made of silver covered with ITO. Solar cells with a transparent ITO back contact exhibit an average efficiency of 10.0%, compared to 9.3% for standard molybdenum back contacts. A 5 nm thick Ga2O3 layer is revealed at the ITO/CIGS interface by transmission electron microscopy and energy dispersive X-ray spectroscopy. When silver is added, the reflective back mirror leads to a JSC improvement of 4.6 mA/cm(2) (from 22.4 to 27.0 mA/cm(2)). These results pave the way for efficient ultrathin CIGS solar cells on reflective back contacts.

【 授权许可】

Free