Photoinduced Electron-Hole Charge Separation, Intrinsic Self-Doping and Novel Device Applications of Q1D Heterojunction Materials: Mixed-Halide MX solids.
Abstract
We have extensively studied, both experimentally and theoretically, the following three mixed-halide systems: (1) PtCl(x) Br (1 - x), (2) PtCl(x) I (1 - x) and (3) PtBr(x) I (1 - x) for a variety of concentrations x. We have obtained direct spectroscopic evidence (vibrational modes) for charge separation from resonance raman (RR) experiments on doped and photoexcited single crystals of PtC1(x). Br (1 - x). In particular, electron polarons preferentially locate on the PtBr segment while hole polarons are trapped within PtCl segments. This polaron charge selectivity, which is potentially very useful for photovoltaic device applications, is demonstrated within theoretical calculations based on a discrete, 3/4-filled, two-band, tight-binding, extended Peierls-Hubbard model, showing strong hybridization of PtCl and PtBr electronic bands as the driving force for separation. In contrast to PtCl(x) Br (1 - x), we find that both the PtCl(x) I (1 - x) and the PtCl(x) Br (1 - x) systems exhibit qualitatively different behavior, such as intrinsic self doping. In other words, our simulations predict that electronic charge is spontaneously removed from the PtI segment and injected into the PtCl (or PtBr) segment, thus creating hole defects in PtI and electron defects (polarons/bipolarons) in PtCl (or PtBr).... Mixed- halide system, Resonance raman.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1993
- Accession Number
- ADA264714
Entities
People
- A. R. Bishop
- Akrati Saxena
- J. T. Gammel
- L. A. Worl
- X. Z. Huang
Organizations
- Naval Command, Control and Ocean Surveillance Center