Title :
High-efficiency Cd2SnO4/Zn2SnO4/Znx Cd1-xS/CdS/CdTe polycrystalline thin-film solar cells
Author :
Wu, X. ; Ribelin, R. ; Dhere, R.G. ; Albin, D.S. ; Gessert, T.A. ; Asher, S. ; Levi, D.H. ; Mason, A. ; Moutinho, H.R. ; Sheldon, P.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO, USA
Abstract :
CdTe-based thin-film solar cells have been limited to the conventional SnO2/CdS/CdTe device structure. In this paper, we report a modified device structure consisting of Cd2SnO 4/Zn2SnO4/ZnxCd1-x S/CdS/CdTe layers, that yields improved performance and reproducibility. Cadmium stannate (Cd2SnO4, or CTO) transparent conductive oxide (TCO) films have several significant advantages over conventional SnO2 films. CTO-based CdTe cells have approximately 1 mA/cm2 higher Jsc than SnO 2-based CdTe cells. Integrating zinc stannate (Zn2SnO4, or ZTO) into the device as a buffer layer helps maintain high Voc and fill factor when reducing CdS thickness to improve Jsc. XPS and SIMS results show substantial interdiffusion between the CdS and ZTO layers. This feature can be used to optimize device performance and reproducibility. We have fabricated a Cd2SnO4/Zn2SnO4/Znx Cd1-xS/CdS/CdTe cell with an NREL-confirmed total-area efficiency of 15.8%
Keywords :
II-VI semiconductors; X-ray photoelectron spectra; cadmium compounds; chemical interdiffusion; secondary ion mass spectroscopy; semiconductor thin films; solar cells; tin compounds; zinc compounds; 15.8 percent; Cd2SnO4; Cd2SnO4-Zn2SnO4 -ZnCdS-CdS-CdTe; Cd2SnO4/Zn2SnO4/Zn xCd1-xS/CdS/CdTe solar cells; CdS thickness reduction; SIMS; XPS; Zn2SnO4; buffer layer; cadmium stannate; high Voc; high fill factor; high-efficiency; interdiffusion; polycrystalline thin-film solar cells; total-area efficiency; transparent conductive oxide films; zinc stannate; Absorption; Annealing; Argon; Cadmium; Conductivity; Current density; Glass; Microstructure; Optical films; Zinc;
Conference_Titel :
Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE
Conference_Location :
Anchorage, AK
Print_ISBN :
0-7803-5772-8
DOI :
10.1109/PVSC.2000.915873
