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Research Abstracts Online
January 2008 - March 2009

University of Minnesota Twin Cities
Institute of Technology
Department of Chemistry

PI: Xiaoyang Zhu

Charge-Transfer Exciton at the Interface of Organic Semiconductors

The break-up of an exciton (a photo-excited electron-hole pair) at the interface between two different organic semiconductors is a crucial, yet poorly understood process in prototype organic solar cells. This project investigates a simplified model of the potential landscape at the interface of an organic semiconductor and vacuum, which the researchers studied experimentally using two-photon photoelectron spectroscopy. After the electron leaves the semiconductor it remains bound by two forces: first, the image force due to the polarizability of the organic semiconductor, and second, the Coulomb force due to the localized positive charge (hole) left inside the molecular semiconductor. The binding energies of the lowest-lying states and the symmetry of the wave functions are calculated by numerically solving the three-dimensional time-independent Schrödinger equation. Recent results are in good agreement with experimental binding energies.

Group Members

Matthias Muntwiler, Research Associate
William Tisdale, Graduate Student
Qingxin Yang, Research Associate