Literature Seminar Abstract

Semiconductor nanoparticles (NPs) are used for a wide variety of applications, including sensing, photocatalysis, and optoelectronics. To optimize their utility for these applications, charge carriers must be able to flow efficiently through the material. However, semiconductor NPs exhibit inherent structural and electronic defects that can trap charge carriers and prevent them from being collected. Understanding the chemical nature of these defects is imperative in order to implement these materials in devices. Defect-mediated energy transfer between a semiconductor NP and an acceptor molecule is a label-free method that can be used to gain insight on the defect states in a material. Dayal and Burda demonstrated defect-mediated energy transfer between CdSe quantum dots (QDs) and phthalocyanine.¹ They showed a non-linear dependence of energy transfer on spectral overlap and QD size, and attributed it to the presence of defect states within the quantum dots. They then altered the surfaces of the CdSe QDs with ZnS shells and showed that passivated QDs do not participate in defect-mediated energy transfer, from which they concluded the defects must be near the surface. The application of their findings could yield knowledge about the electronic structure and the flow of charge carriers across a broad range of materials, which can then be optimized for devices.

(1)        Dayal, S.; Burda, C. Surface Effects on Quantum Dot-Based Energy Transfer. J. Am. Chem. Soc. 2007, 129 (25), 7977–7981.