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Title: Effects of sodium and potassium on the photovoltaic performance of CIGS solar cells

Here, the deliberate introduction of K and Na into Cu(In, Ga)Se 2 (CIGS) absorbers was investigated by varying a combination of an SiO 2 diffusion barrier, coevaporation of KF with the CIGS absorber, and a KF postdeposition treatment (PDT). Devices made with no diffusion barrier and KF coevaporation treatment exhibited the highest photovoltaic conversion efficiency with the smallest overall distribution in key current density-voltage (J-V) performance metrics. Out-diffusion of Na and K from the substrate, KF coevaporation, and KF PDT all increased carrier concentration, open-circuit voltage, fill factor, and power conversion efficiency. Quantum-efficiency analysis of devices highlighted the greatest loss in the short-circuit current density due to incomplete absorption and collection. Secondary ion mass spectrometry illustrated the efficacy of the SiO 2 film as a sodium and potassium diffusion barrier, as well as their relative concentration in the absorber. Introduction of KF appeared to enhance diffusion of Na from the substrate, in agreement with previous studies.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. Colorado State Univ., Fort Collins, CO (United States)
  2. Univ. of Florida, Gainesville, FL (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-68549
Journal ID: ISSN 2156-3381
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2156-3381
Publisher:
IEEE
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); SunShot Initiative
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; CIGS; passivation; photovoltaic (PV) cells; thin films
OSTI Identifier:
1358338