High rate (~7nm/s), atmospheric pressure deposition of ZnO front electrode for Cu(In,Ga)Se sub(2) thin-film solar cells with efficiency beyond 15

• Published in: Progress in photovoltaics Vol. 21; no. 8; pp. 1559 - 1566
• Main Authors: Illiberi, Andrea, Grob, Frank, Frijters, Corne, Poodt, Paul, Ramachandra, Ram, Winands, Hans, Simor, Marcel, Bolt, Pieter Jan
• Format: Journal Article
• Language: English
• Published: 01-12-2013
• Subjects: ALUMINUM OXIDE; Atmospheric pressure; Barometric pressure; COPPER INDIUM SELENIDE; COPPER SELENIDE; DEPOSITION; Electrodes; Photovoltaic cells; PRESSURE; Solar cells; THIN FILMS; ZINC OXIDE
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.2423

Undoped zinc oxide (ZnO) films have been grown on a moving glass substrate by plasma-enhanced chemical vapor deposition at atmospheric pressure. High deposition rates of ~7nm/s are achieved at low temperature (200 degree C) for a substrate speed from 20 to 60mm/min. ZnO films are highly transparent in the visible range (90%). By a short (~minute) post-deposition exposure to near-ultraviolet light, a very low resistivity value of 1.6.10 super(-3) Omega cm for undoped ZnO is achieved, which is independent on the film thickness in the range from 180 to 1200nm. The photo-enhanced conductivity is stable in time at room temperature when ZnO is coated by an Al sub(2)O sub(3) barrier film, deposited by the industrially scalable spatial atomic layer deposition technique. ZnO and Al sub(2)O sub(3) films have been used as front electrode and barrier, respectively, in Cu(In,Ga)Se2 (CIGS) solar cells. An average efficiency of 15.4 plus or minus 0.2% (15 cells) is obtained that is similar to the efficiency of CIGS reference cells in which sputtered ZnO:Al is used as electrode. Copyright [copy 2013 John Wiley & Sons, Ltd. Undoped zinc oxide (ZnO) has been grown by plasma-enhanced chemical vapor deposition at atmospheric pressure. After post-deposition exposure to near-ultraviolet light, a low value of resistance (15 Omega /sq) is achieved in films that are highly transparent (90 %) in the visible range. ZnO is used as front electrode in Cu(InGa)Se2 solar cells achieving an efficiency of 15.4%, similar to reference cells with a sputtered Al:ZnO electrode.