The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells
Abstract
We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO2) 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 TiO2 thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO2 thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO2 form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. We show that the optimum TiO2 thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO2 is amorphous, in agreement with the device measurements.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 14, 2016
- Source ID
- 10.1063/1.4944049
Entities
People
- Adam E Colbert
- David Ginger
- David Moerman
- Hyungchul Kim
- Samuel Graham
Organizations
- Georgia Tech
- Office of Naval Research
- United States Department of Energy
- University of Washington