eprintid: 36876
rev_number: 16
eprint_status: archive
userid: 8423
dir: disk0/00/03/68/76
datestamp: 2025-07-29 14:04:25
lastmod: 2025-07-31 13:00:11
status_changed: 2025-07-29 14:04:25
type: doctoralThesis
metadata_visibility: show
creators_name: Valsalan, Parvathi
title: Strong Light-Matter Coupling with N-Heteropolycycles
divisions: i-120300
adv_faculty: af-12
abstract: In optical microcavities, strong light–matter coupling gives rise to exciton polaritons,
hybrid light–matter states formed through the interaction between confined photons and
molecular excitons. While the criteria for achieving strong coupling are well established, the
influence of molecular properties on lower polariton (LP) population and polariton-mediated
energy transfer remains underexplored.
This thesis investigates the potential of N-heteropolycycle-based systems as versatile
platforms for strong light–matter coupling in organic microcavities, aiming to deepen in-
sight into exciton–polariton phenomena in molecular materials. Three primary objectives
were pursued. First, the viability of N-heteropolycycles for polariton formation was estab-
lished using thioether-functionalized tetraazaperylene (TFTAP) derivatives (Butyl-, Benzyl-
, and p-methoxybenzyl (PMB)-TFTAP) embedded in polystyrene matrices within metal-
clad microcavities. Angle-resolved reflectivity and photoluminescence (PL) spectroscopy
confirmed polariton formation, with Rabi splitting energies ranging from 40 to 241 meV—
comparable to established organic systems. Polariton properties were tuned via cavity thick-
ness and emitter concentration, validating the collective and coherent nature of the coupling.
Second, polariton relaxation pathways in vibronically active tetraazacoronene (TAC) trimer
systems were explored, revealing detuning-dependent contributions from radiative pump-
ing (RP) and vibrationally assisted scattering (VAS). Spectral signatures indicated that reso-
nance between states and vibronic or Raman-active modes enhances LP population, offering
mechanistic insights relevant to low-threshold polariton lasing. Third, polariton-mediated
energy transfer was investigated in multilayer microcavities incorporating donor–acceptor
pairs (ATTO 680–IRDye and ATTO 655–IRDye). Systems with larger exciton energy off-
sets exhibited enhanced acceptor emission due to modulation of polariton composition, es-
tablishing energy offset as a key parameter for efficient energy transfer design.
date: 2025
id_scheme: DOI
id_number: 10.11588/heidok.00036876
ppn_swb: 1932221077
own_urn: urn:nbn:de:bsz:16-heidok-368768
date_accepted: 2025-07-04
advisor: HASH(0x55602a6ffb60)
language: eng
bibsort: VALSALANPASTRONGLIGH20250521
full_text_status: public
place_of_pub: Heidelberg
citation:   Valsalan, Parvathi  (2025) Strong Light-Matter Coupling with N-Heteropolycycles.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/36876/1/Parvathi%20Valsalan_Final_Thesis.pdf