Current interest in quantum dot sensitized solar cells has motivated studies of electron transfer reactions at the quantum dot-metal oxide (QD-MO) junction. Anchoring QDs to an MO substrate typically involves a bi-functional linker molecule, such as 3-mercaptopropionic acid (3-MPA) that bridges between QD and MO. This linker modifies the QD surface through the creation of electron trapping states. Herein we monitor the effects of �-alanine (�-Ala) binding to the QD surface via the steady-state absorption and emission properties of colloidal CdSe in toluene suspension. We demonstrate the remediation of electron traps on the QD surface through the enhancement of fluorescence quantum yield for CdSe/�-Ala solutions. This trap remediation arises from the electron donating (Lewis-basic) nature of the amine group on �-Ala. Transient absorption measurements on three methods for adsorbing CdSe onto TiO2 reveal the effect that �-Ala binding has on electron transfer rates at this interface: CdSe-TiO2 (direct deposition, ket = 1.5 � 1010 s-1), CdSe-linker-TiO2 (Initial linker molecule attachment to TiO2 so that �-Ala modification of the surface is minimal, ket = 2.4 � 109 s-1) or CdSe-encapsulation-TiO2 (full �-Ala encapsulation of QDs in solution prior to deposition, ket = 6.4 � 108 s-1). These results show that the surface chemistry of pre-synthesized CdSe QDs plays an important role in mediating electron transfer at the QD-MO interface.

Influence of surface chemistry on electron transfer at the CdSe-TiO<sub>2</sub> interface

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Influence of surface chemistry on electron transfer at the CdSe-TiO2 interface

Influence of surface chemistry on electron transfer at the CdSe-TiO₂ interface