Characteristics of Zn1−xMgxO:B and its application as transparent conductive oxide layer in Cu(In,Ga)(S,Se)2 solar cells with and without CdS buffer layer.

Highlights • Zn 1− x Mg x O:B (BZMO) was prepared by MOCVD method. • Optical and electrical properties of BZMO were investigated. • BZMO was applied as TCO of CIGSSe solar cell, where K-treated CIGSSe is absorber. • 21.1%-efficient CdS-buffer CIGSSe solar cell was fabricated. • 20.2%-efficient Cd-free CIGSSe solar cell was obtained by all-dry process. Abstract Zn 1− x Mg x O:B (BZMO) films were deposited by metal organic chemical vapor deposition (MOCVD). Their optical and electrical properties were investigated for suitability as transparent conductive oxide (TCO) of the Cu(In,Ga)(S,Se) 2 (CIGSSe) solar cells. It is disclosed that with the increase in the [Mg]/([Mg] + [Zn]) of the BZMO up to 0.12 the optical band-gap energy (E g) is increased to 3.52 eV, and the resistivity is reduced to about 3.1 × 10−3 Ω·cm owing to the increase in the Hall mobiltity. Moreover, the severe free-carrier absorption in the BZMO film is not observed. The BZMO is consequently appropriate as the TCO layer of the CIGSSe solar cells. The K-treated CIGSSe layers were applied as the absorbers of the solar cells. As a result, the 21.1%-efficient CIGSSe solar cell with a structure of Zn 0.88 Mg 0.12 O:B/CdS/CIGSSe/Mo/glass is obtained. In addition, the 20.2%-efficient Cd-free CIGSSe solar with a structure of Zn 0.88 Mg 0.12 O:B/Zn 0.80 Mg 0.20 O/CIGSSe/Mo/glass, fabricated by all-dry process, is realized with high short-circuit current density (J SC) of 39.7 mA/cm2. The high J SC is attributable to no optical loss in CdS buffer layer, no severe free carrier absorption, and the increased E g of the BZMO layer. [ABSTRACT FROM AUTHOR]