High-efficiency CuIn<i>x</i>Ga1−<i>x</i>Se2 solar cells made from (In<i>x</i>,Ga1−<i>x</i>)2Se3 precursor films

TLDR

The authors co‑evaporated In, Ga, and Se to form (Inx,Ga1−x)2Se3 precursor films, then converted them to CuInxGa1−xSe2 by exposing them to a Cu and Se flux. The resulting CuInxGa1−xSe2 films were smooth, densely packed, and exhibited depth‑graded Ga content, and devices fabricated from them achieved a record 15.9 % total‑area efficiency for non‑single‑crystal thin‑film solar cells while remaining tolerant to compositional variations.

Abstract

In, Ga, and Se were coevaporated to form precursor films of (Inx,Ga1−x)2Se3. The precursors were then converted to CuInxGa1−xSe2 by exposure to a flux of Cu and Se. The final films were smooth, with tightly packed grains, and had a graded Ga content as a function of film depth. Photovoltaic devices made from these films showed good tolerance in device efficiency to variations in film composition. A device made from these films resulted in the highest total-area efficiency measured for any non-single-crystal, thin-film solar cell, at 15.9%.