Title :
Evaluation of micro- and nanoscale uniformity in all-PVD Cu(In,Ga)Se2 solar cells
Author :
Kimball, Gregory M. ; Mackie, N. ; Parker, Michael ; Bayman, Atiye
Author_Institution :
MiaSole Hi-Tech Corp., Santa Clara, CA, USA
Abstract :
Over the past several years, advances in manufacturing for thin film Cu(In,Ga)Se2 (CIGS) devices have enabled volume production of high efficiency solar material with good repeatability and uniformity. In this study, quantitative analysis of several advanced imaging techniques was used to evaluate the uniformity of electronic properties for all-PVD CIGS solar cells. Combined EL and DLIT analysis suggests that series resistance in the top electrode constitutes the strongest nonuniformity, which is estimated to contribute about 2.5% relative efficiency loss. High-resolution EL image analysis shows a highly uniform lateral band gap distribution with standard deviations of minimum band gap values <;2 meV. Finally, EBIC image analysis shows collection lengths of 1.5 ± 0.2 μm, indicating high collection probability throughout the depth of the CIGS absorber layer and at grain boundaries. Highly uniform micro- and nanoscale electronic properties have enabled all-PVD CIGS solar modules to reach a certified efficiency of 15.7% over 0.97 m2 aperture area.
Keywords :
copper compounds; electrochemical electrodes; grain boundaries; image resolution; indium compounds; power engineering computing; probability; solar cells; ternary semiconductors; Cu(In-Ga)Se2; DLIT analysis; ERIC image analysis; absorber layer; all-PVD CIGS solar cell module; efficiency 15.7 percent; electronic property; grain boundary; high efficiency solar material; high-resolution EL image analysis; highly uniform lateral band gap distribution; microscale uniformity; nanoscale uniformity; probability; relative efficiency loss; top electrode; volume production; Electrodes; Imaging; Nanoscale devices; Photonic band gap; Photovoltaic cells; Resistance; Standards; CIGS; DLIT; EBIC; EL; uniformity;
Conference_Titel :
Photovoltaic Specialist Conference (PVSC), 2014 IEEE 40th
Conference_Location :
Denver, CO
DOI :
10.1109/PVSC.2014.6925504