Energy transfer processes in organic molecular semiconductors
<p>Organic semiconductors exhibit excellently suited material properties for a variety of applications and offer the possibility of low-cost and large-scale production. This thesis analyses photonic properties of several organic semiconductors, which are of great interest for different applica...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
2020
|
| Subjects: |
| Summary: | <p>Organic semiconductors exhibit excellently suited material properties for a variety
of applications and offer the possibility of low-cost and large-scale production. This
thesis analyses photonic properties of several organic semiconductors, which are of
great interest for different applications. To explore these materials, a combination
of steady-state and time-resolved optical measurement techniques is employed and
energy transfer dynamics within organic semiconductors are modelled. Research
was focused on the following areas:</p>
<p>The influence of the fraction of chain segments that adapt β-phase conformation
on film microstructure of thin films of the blue-emitting polymer PFO is consistently
investigated for the first time. An analysis of emission and absorption properties of
PFO films with systematically varying β-phase content indicates that with increasing
β-phase in PFO films, the chain conformation becomes more planar and includes
more repeat units.</p>
<p>Energy transfer, which occurs upon photoexcitation from glassy-phase to β-phase
chain segments in PFO thin films is evaluated in terms of Förster resonant energy
transfer theory. Differences in Förster radii calculated from ultrafast emission dynamics
and spectral overlap between steady-state emission and absorption indicate that the
energy transfer process is influenced by exciton diffusion within the glassy phase.</p>
<p>Parasitic absorption of light in a molecular sun-facing charge extraction layer
(CTL) of a metal halide perovskite (MHP)-based solar cell structure is addressed.
Experimentally observed energy transfer between layers of photoexcited conjugated
polymers and a MHP layer is combined with modelling the efficiency of the energy
transfer process. Efficient energy transfer is found to counteract parasitic light
absorption in the CTL for thin layers (≤ 10 nm) and/or high PLQE materials.</p>
<p>Morphological changes in films of the hole-transport material P3HT deposited on
MAPbI<sub>3</sub>
are explored. Changes in aggregation are observed through careful analysis
of absorption and emission spectra from P3HT films of varying thickness and spin
speed during their fabrication on a MAPbI<sub>3</sub>
layer.</p> |
|---|