Download or read book NREL Determines Long-Lived Carriers and Differences in CdTe Superstrate and Substrate Cells (Fact Sheet). written by and published by . This book was released on 2012 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: NREL study may provide future guidance in improving CdS/CdTe photovoltaic device performance. The majority of minority carrier lifetime (MCL) studies performed on CdS/CdTe photovoltaic (PV) devices have correlated device performance primarily with the fast decay observed in time-resolved photoluminescence (TRPL) measurements (t1). This decay is believed to be associated primarily with recombination in depletion width (W{sub D}), and therefore should be a good indicator of device quality if carrier generation occurs primarily within WD. However, although previous studies have shown that t1 can be a good indicator of broad device quality, it does not correlate as well with small changes in device performance and/or with differences observed between superstrate and substrate devices. Researchers at the National Renewable Energy Laboratory (NREL) have shown that in this case, the parameter t2 (from the longer-term decay of TRPL) may not only provide a better correlation with device open-circuit voltage (V{sub OC}) for superstrate devices but may also provide guidance for inter-comparison with alternative device designs (e.g., substrate devices). It is also suggested that previous studies may yield added value if a larger number of TRPL parameters (i.e., t1, t2, and respective amplitudes) are re-examined as a function of device performance. The parameter t2 may not only provide a better correlation with device VOC for superstrate devices but may also provide guidance for inter-comparison with alternative device designs (e.g., substrate devices).