Xylindein is an organic pigment derived from Chlorociboria aeruginascens and C. aeruginosa fungi that has
shown promise as an organic semiconductor. Preliminary estimates of charge carrier mobilities (CCMs) on
the order of 0.1 cm2/Vs were calculated from early tests on xylindein thin films, and photocurrents were
also observed under laser stimulation. As part of the ongoing effort to characterize xylindein and improve
its quality as a possible semiconductor, a broad set of experiments were performed testing the optical and
electronic properties of xylindein in solutions and bulk films, and attempts were made, using techniques like
solvent vapor annealing, to improve the electronic quality of xylindein thin films (as measured by CCM).
In addition, the electronic properties of xylindein and some of its isomers were calculated using Gaussian
09. The details of these experiments and their results are outlined in this report, with comparisons made
between the observed characteristics of xylindein and those of other organic semiconductors.
Xylindein absorbs strongly in the visible range, with a peak molar absorptivity near 8600 1/Mcm, but
fluoresces very little compared to other organic semiconductors, indicating some strong mechanism for
non-radiative decay in both dissolved and bulk xylindein. Xylindein shows strong signs of intermolecular
hydrogen bonding through both a 30-60 nm red shift in the absorption spectrum in protic solvents as well as
a tendency to start showing bulk properties in spectroscopic data at a lower range of solution concentrations
than other organic semiconductors. The high preliminary charge carrier mobilities observed were not successfully
replicated, but efforts to improve thin film quality were unsuccessful or even counterproductive.
Computational results for enthalpy of formation show a difference of less than 0.1 kcal/mol between
xylindein and one of its isomers, suggest that xylindein could potentially spontaneously self-isomerize. The
isomers of xylindein were also calculated to have vastly different HOMO-LUMO gaps, with sizes ranging
from 1.70 to 2.24 eV, than xylindein itself.