The effects of defects in CdTe and CIGS thin film solar cells: Multi-scale investigation of the microstructure and chemistry of individual grains and grain boundaries
EMSL Project ID
48130
Abstract
In recent years, the conversion efficiencies for CdTe and Cu(In, Ga)Se2 (CIGS) thin-film solar cells have increased rapidly, reaching 19.6% and 20.4% for CdTe and CIGS thin-film solar cells, respectively [1]. This remarkable performance of polycrystalline CdTe and CIGS solar cells is truly exceptional because polycrystalline solar cells are usually expected to exhibit poor performance compared to their single-crystalline counterparts [2,3]. The often observed poor performance of polycrystalline materials is commonly attributed to the existence of grain boundaries (GBs) and intra-grain inhomogeneities, which are usually effective recombination centers for photon-generated electrons and holes [4,5] and scattering centers for electrical transport [6,7]. Thus, the behavior of GBs and intra-grain defects hold the key for unraveling the origin of the superior performance of CdTe and CIGS thin-film solar cells. To understand the role of GBs and intra-grain defects, it is necessary to investigate the chemistry and microstructure using high resolution techniques with good chemical sensitivity. The goal of this study is a multi-scale characterization of the composition and microstructure of grain boundaries and intra-grain regions. Specifically, we would like to propose to do some proof of principle experiements to investigate the variation of Cu, In and Ga concentrations on and off grain boundaries in Cu(In, Ga)Se2 high efficiency solar cells using nano-SIMS. Further, we would like to investigate the structural properties of grain boundaries and intra-grain defects at the atomic level using aberration-corrected STEM. If this preliminary investigation is successful, we plan on writing a general or science theme proposal in the near future to continue the work. Rapid access is needed as we are having our annual DOE program review in two months. Having preliminary data for that review would be extremely helpful to plan our research for the next fiscal year.
Project Details
Project type
Limited Scope
Start Date
2013-10-04
End Date
2013-11-21
Status
Closed
Released Data Link
Team
Principal Investigator