Energy level alignment, electron injection, and charge recombination characteristics in CdS/CdSe cosensitized TiO2 photoelectrode

Abstract

The band-edge levels of CdS-, CdSe-, and CdS/CdSe-sensitized TiO2 electrodes were determined by ultraviolet photoelectron spectroscopy (UPS) to explore the reason leading to the high performance of the TiO2/CdS/CdSe electrode. The obtained UPS results show the stepwise energy level in the TiO2/CdS/CdSe electrode, indicating energy level alignment occurrence between CdS and CdSe in the TiO2/CdS/CdSe. Time-resolved photoluminescence and open-circuit photovoltage decay experiments reveal that the photogenerated electrons in the TiO2/CdS/CdSe have higher injection efficiency, but lower recombination rate to the electrolyte, attributable to the stepwise structure of band-edge levels constructed by the effect of the energy level alignment.

Effect of Different Sensitization Technique on the Photoconversion Efficiency of CdS Quantum Dot and CdSe Quantum Rod Sensitized TiO2 Solar Cells

“…For CdS/CdSe co-sensitized electrode such decay start after 550 nm for QRs 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 20 it is observed that the CdS/CdSe CB is -3.49 eV due to the Fermi-level alignment 39 showing the CB above of the TiO 2 CB obtaining a favorable electron injection and increase of V oc from 542 mV to 575 mV. …”

Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell

“…Metal oxide semiconductors are generally stable in aqueous environments and are cheap which leads them to be widely promoted as among the most promising materials for solar-photon-driven water splitting. 1,6,7 Although a large number of semiconductor materials have been developed as good candidates for photoelectrodes in past decades, 8,9 the solar-hydrogen conversion efficiencies of these recognized materials are still not high enough due to low light absorption and high recombination of electron-hole pairs. 5,10 Therefore, the design of efficient solar-active nanostructured PEC cell has been the topic of considerable research.…”

Effect of Photoanode Design on the Photoelectrochemical Performance of Dye-Sensitized Solar Cells Based on SnO2 Nanocomposite

“…The OCVD technique was used to monitor the subsequent decay of photovoltage after turning off the illumination. Figure 7a shows the voltage decay curves of the DSSCs based on SNC and SNC_Z photoanodes and the calculated τ e using Equation (1) [33,34]:…”