Orbital Topology Controlling Charge Injection in Quantum-Dot-Sensitized Solar Cells.
Quantum-dot-sensitized solar cells are emerging as a promising development of dye-sensitized solar cells, where photostable semiconductor quantum dots replace molecular dyes. Upon photoexcitation of a quantum dot, an electron is transferred to a high-band-gap metal oxide. Swift electron transfer is crucial to ensure a high overall efficiency of the solar cell. Using femtosecond time-resolved spectroscopy, we find the rate of electron transfer to be surprisingly sensitive to the chemical structure of the linker molecules that attach the quantum dots to the metal oxide. A rectangular barrier model is unable to capture the observed variation. Applying bridge-mediated electron-transfer theory, we find that the electron-transfer rates depend on the topology of the frontier orbital of the molecular linker. This promises the capability of fine tuning the electron-transfer rates by rational design of the linker molecules.
‡Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen Ø, Denmark.
Thorsten
T
Hansen
Karel
K
Žídek
Kaibo
K
Zheng
¶Department of Chemistry, Qena Faculty of Science, South Valley University, Qena 83523, Egypt.
Mohamed
M
Abdellah
Pavel
P
Chábera
Petter
P
Persson
Tõnu
T
Pullerits
bridge-mediated electron-transfer theory; electron transfer; femtosecond time-resolved spectroscopy; frontier orbital; quantum-dot-sensitized solar cells