Electronic Properties of Optically Switchable Photochromic Diarylethene Molecules at the Interface with Organic Semiconductors

Abstract

Light-switching induced changes in the electronic properties of photochromic diarylethene, i.e., 1,2-bis(2-methyl-5-p-tolylthiophen-3-yl)cyclopent-1-ene (DAE1), thin films at interfaces to a gold electrode and two polymer semiconductors were investigated by direct and inverse photoelectron spectroscopy.

Modulating the luminance of organic light-emitting diodes via optical stimulation of a photochromic molecular monolayer at transparent oxide electrode

“…Indeed, different energies of the highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) level have been reported for DAEs in their open and closed form. 28,30,45,46 The ability to optically modulate the energy of these frontier molecular orbital levels ultimately should enable to modulate and control the carrier injection/extraction barrier at the ITO interface.…”

“…29 The extended valence region measured via UPS exhibits the molecular fingerprints of the DAE molecule ( peaks at 5 and 7 eV). 28,46 From the zoom of the valence region close to the Fermi level (BE = 0 eV) it is possible to measure the onset of the HOMO (i.e., the hole injection barrier). For PA-DAE in open form the hole injection barrier is 1.5 eV.…”

“…2a) and to the transport gap investigated by inverse photoemission spectroscopy of related diarylethene derivatives. 46…”