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Title: The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells

We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO 2) layers grown via plasma-enhanced atomic layer deposition (PE-ALD). We find an optimal thickness of PE-ALD-grown titania by tracking performance, which initially increases, peaks, and eventually decreases with increasing TiO 2 thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO 2 thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO 2 form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. Here, we show that the optimum TiO 2 thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO 2 is amorphous, in agreement with the device measurements.
Authors:
ORCiD logo [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry
  2. Georgia Inst. of Technology, Atlanta, GA (United States). School of Mechanical Engineering
Publication Date:
Grant/Contract Number:
EE0004946
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 11; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Stanford Univ., CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 25 ENERGY STORAGE; 14 SOLAR ENERGY
OSTI Identifier:
1468780
Alternate Identifier(s):
OSTI ID: 1241567