Size-Dependent Electron Transfer from PbSe Quantum Dots to SnO2 Monitored by Picosecond Terahertz Spectroscopy

作者：Canovas Enrique^*; Moll Puck; Jensen Soren A; Gao Yunan; Houtepen Arjan J; Siebbeles Laurens D A; Kinge Sachin; Bonn M

来源：Nano Letters, 2011, 11(12): 5234-5239.

DOI：10.1021/nl202550v

• QD sensitized solar cell
• THz spectroscopy
• electron transfer
• Marcus theory
• PbSe QDs

We report the direct and unambiguous determination of electron transfer rates and efficiencies from PbSe quantum dots (QDs) to mesoporous SnO2 films. We monitor the time-dependent electron density within the oxide with picosecond time resolution using Terahertz spectroscopy, following optical excitation of the QDs using a femtosecond laser pulse. QD-oxide electron transfer occurs with efficiencies of similar to 2% in our samples under 800 nm pumping with a marked dependence on QD size, ranging from similar to 100 ps injection times for the smallest, similar to 2 nm diameter QDs, to similar to 1 ns time scale for similar to 7 nm QDs. The size-dependent electron transfer rates are modeled within the framework of Marcus theory and the implications of the results for device design are discussed.

• 出版日期2011-12