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Title: Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe2 solar cells

Journal Article · · Progress in Photovoltaics
DOI:https://doi.org/10.1002/pip.3022· OSTI ID:1471293
 [1]; ORCiD logo [2];  [3];  [2];  [3]
  1. Univ. of Florida, Gainesville, FL (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Florida, Gainesville, FL (United States)
+ Show Author Affiliations

K incorporation within grain boundaries, grain interiors, and interfaces has been studied within CuInSe2 solar cells to better understand the beneficial or detrimental role of K distribution among these regions in chalcopyrite–based solar cells. Solar cells have been fabricated with intentional K introduction into specific regions of the device including the CuInSe2/CdS interface (CuInSe2/KInSe2/CdS) and the grain interiors (Cu0.93K0.07InSe2/CdS). A control CuInSe2/CdS device was also studied to separate effects of K originating from the soda–lime glass substrate from those of intentionally introduced K. The experiment was designed to understand K effects in Cu(In,Ga)Se2 solar cells while mitigating complications from multiple elements in the 3+ site. The distribution of all elements within these samples has been directly observed with sub–nm resolution via atom probe tomography. In addition, electron beam–induced current measurements have been performed to correlate the atom probe tomography compositional profiles to the nanoscale carrier collection properties. The experiments show that a large decrease in the Cu/In ratio at the CdS interface can be achieved by forming KInSe2 at the absorber surface, which drastically improves the device efficiency. The results presented here show a direct link between K concentration, Cu depletion, and In accumulation, such that the Cu/In ratio significantly reduces with K incorporation. In conclusion, the findings help clarify the mechanism behind K–induced efficiency enhancement.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
Grant/Contract Number:
AC36-08GO28308; DE‐AC36‐08GO28308; AC05-00OR22725
OSTI ID:
1471293
Alternate ID(s):
OSTI ID: 1441017; OSTI ID: 1454388
Report Number(s):
NREL/JA-5K00-71548
Journal Information:
Progress in Photovoltaics, Vol. 26, Issue 10; ISSN 1062-7995
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 18 works
Citation information provided by
Web of Science

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Cited By (2)

Efficiency Improvement of Near‐Stoichiometric CuInSe 2 Solar Cells for Application in Tandem Devices journal July 2019
No Evidence for Passivation Effects of Na and K at Grain Boundaries in Polycrystalline Cu(In,Ga)Se 2 Thin Films for Solar Cells journal May 2019

Figures / Tables (16)

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Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
chalcopyrite
CuInSe2
Cu(In
Ga)Se2
potassium
atom probe tomography
electron beam induced current
electron beam-induced current