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Title: Mapping photovoltaic performance with nanoscale resolution

Photo-conductive AFM spectroscopy (‘pcAFMs’) is proposed as a high-resolution approach for investigating nanostructured photovoltaics, uniquely providing nanoscale maps of photovoltaic (PV) performance parameters such as the short circuit current, open circuit voltage, maximum power, or fill factor. The method is demonstrated with a stack of 21 images acquired during in situ illumination of micropatterned polycrystalline CdTe/CdS, providing more than 42,000 I/V curves spatially separated by ~5 nm. For these CdTe/CdS microcells, the calculated photoconduction ranges from 0 to 700 picoSiemens (pS) upon illumination with ~1.6 suns, depending on location and biasing conditions. Mean short circuit currents of 2 pA, maximum powers of 0.5 pW, and fill factors of 30% are determined. The mean voltage at which the detected photocurrent is zero is determined to be 0.7 V. Significantly, enhancements and reductions in these more commonly macroscopic PV performance metrics are observed to correlate with certain grains and grain boundaries, and are confirmed to be independent of topography. Furthermore, these results demonstrate the benefits of nanoscale resolved PV functional measurements, reiterate the importance of microstructural control down to the nanoscale for 'PV devices, and provide a widely applicable new approach for directly investigating PV materials.
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1]
  1. Univ. of Connecticut, Storrs, CT (United States)
  2. Univ. of Texas at El Paso, El Paso, TX (United States); Sandia National Lab. (SNL-NM), MEMS Technologies, Albuquerque, NM (United States)
  3. Sandia National Lab. (SNL-NM), MEMS Technologies, Albuquerque, NM (United States)
  4. University of Texas at El Paso, Electrical and Computer Engineering, El Paso TX USA
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1062-7995; 558235
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Progress in Photovoltaics
Additional Journal Information:
Journal Volume: 93; Journal Issue: 3; Journal ID: ISSN 1062-7995
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
14 SOLAR ENERGY; 77 NANOSCIENCE AND NANOTECHNOLOGY Atomic Force Microscopy (AFM); CdTe; photovoltaic; nanoscale; characterization