login

Search documents

Browse topics

Document details

 
Title:
 
Charge Generation and Selective Separation at PbS-Quantum Dot / Metal Oxide Interfaces
 
Author(s):
 
V. Hinrichs, S. Fengler, R. Lascova, L. Kulyuk, T. Dittrich, M.C. Lux-Steiner, M. Rusu
 
Keywords:
 
Photoluminescence, TiO2, Interface(s), Quantum Dots, PbS
 
Topic:
 
MATERIAL STUDIES, NEW CONCEPTS, ULTRA-HIGH EFFICIENCY AND SPACE TECHNOLOGY
Subtopic: New Materials and Concepts for Cells
Event: 28th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1AV.2.37
 
Pages:
 
349 - 351
ISBN: 3-936338-33-7
Paper DOI: 10.4229/28thEUPVSEC2013-1AV.2.37
 
Price:
 
 
0,00 EUR
 
Document(s): paper
 

Abstract/Summary:


Charge separation and transfer at the interface between layers of oleic acid capped PbS quantum dots (QDs) and Titanium and Indium Tin oxide (TiO2 and ITO) films were investigated by surface photovoltage (SPV) measurements. Photoluminescence (PL) measurements were performed in order to check for excitonic transitions and determine the QD band gaps. The QDs diameter of 4.2 nm and 5.0 nm were estimated by using the PL band gaps and the theoretical equation derived by Wang et al. [J. Chem. Phys. 87 (1987) 7315]. The SPV spectra of the PbSQDs/ TiO2 system reveal a positive charge on the PbS film surface and show three distinguished regions which demonstrate: (i) the charge separation across QDs, (ii) the electron-injection from QDs into TiO2 and (iii) the fundamental absorption in TiO2. The on-set of the electron injection depends on the QD size (QD band gap): it shifts to lower photon energies for lower QD dimensions (for higher QD band gaps). Thus, a better conduction band alignment is achieved in the latter case. In contrast to PbS-QDs/TiO2, the SPV spectra of the PbS-QDs/ITO structure reveal the negative charge on PbS surface. Moreover, the charge transfer at this interface is not observed. Instead, the SPV peculiarities in the photon energy range 1.4–3.0 eV point out to trapped holes on the ITO surface states.