STUDY OF SURFACE STATES AT THE SEMICONDUCTOR/ELECTROLYTE INTERFACE OF LIQUID-JUNCTION SOLAR CELLS.
Item
-
Title
-
STUDY OF SURFACE STATES AT THE SEMICONDUCTOR/ELECTROLYTE INTERFACE OF LIQUID-JUNCTION SOLAR CELLS.
-
Identifier
-
AAI8401958
-
identifier
-
8401958
-
Creator
-
SIRIPALA, WITHANA P.
-
Contributor
-
Micha Tomkiewicz | F.H. Poliak
-
Date
-
1983
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Physics, Condensed Matter
-
Abstract
-
The existence of surface states at the semiconductor electrolyte interface of photoelectrochemical (PEC) cells plays a major role in determining the performance of the device in regard to the potential distribution and transport mechanisms of photogenerated carriers at the interface. We have investigated the n-TiO(,2)/electrolyte interface using three experimental techniques: relaxation spectrum analysis, photocurrent spectroscopy, and electrolyte electroreflectance (EER) spectroscopy. The effect of Fermi level pinning at the CdIn(,2)SE(,4)/aqueous-polysulfide interface was also studied using EER.;Three distinct surface states were observed at the n-TiO(,2)/aqueous-electrolyte interface. The dominant state, which tails from the conduction band edge, is primarily responsible for the surface recombination of photocarriers at the interface. The second surface state, observed at 0.8 eV below the conduction band of TiO(,2), originates in the dark charge transfer intermediates (TiO(,2)-H). It is proposed that the sub-bandgap (SBG) photocurrent-potential behavior is a result of the mechanism of dynamic formation and annihilation of these surface states. The third surface state was at 1.3 eV below the conduction band of TiO(,2), and the SBG EER measurements show this state is "intrinsic" to the surface. These states were detected with SBG EER and impedance measurements in the presence of electrolytes that can adsorb on the surface of TiO(,2). Surface concentration of these states was evaluated with impedance measurements.;EER measurements on a CdIn(,2)Se(,4)/polysulfide system have shown that the EER spectrum is sensitive to the surface preparation of the sample. The EER signal was quenched as the surface was driven to strong depletion, owing to Fermi level pinning at the interface in the presence of a high density of surface states. The full analysis of this effect enables us to measure the change in the flatband potential, as a function of the electrode potential, and also the energy distribution of these states.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Physics
