Dirk M. Guldi (Friedrich-Alexander-Universität Erlangen-Nürnberg): Materials for adaptive light management; capture, conversion, and storage (In-person only)

Abstract

Adaptive light management materials are a class of advanced functional materials engineered to control the capture, guidance, and storage of light.  These materials dynamically modulate their light absorption in response to external environmental conditions.  In photovoltaic (PV) systems, losses arising from thermalization and sub-bandgap absorption impose fundamental limits on device performance.  For conventional single-junction cells, the theoretical maximum power conversion efficiency is approximately 33%, a constraint defined by the detailed balance limit.  Realizing the full potential of PV technologies therefore requires the development of novel strategies capable of circumventing these intrinsic efficiency boundaries.

Spectral down-conversion is a process in which high-energy photons are converted into lower-energy photons.  Conversely, up-conversion involves the combination of two or more low-energy photons to generate a single higher-energy photon.  Both processes allow materials to utilize photons that would otherwise be lost—either by converting transmitted light into usable wavelengths, thereby enhancing overall device efficiency, or by transforming high-energy photons into wavelengths that are more efficiently absorbed by the active layer.

Acenes, a class of linearly fused aromatic hydrocarbons, stand out as a versatile platform for advanced light management due to their unique photophysical and electronic properties.  They exhibit strong π-conjugation, resulting in high optical absorption across the visible spectrum and efficient fluorescence.  Such characteristics make acenes particularly suitable for spectral down- and up-conversion.  Beyond these photon conversion processes, acenes also facilitate energy down- and up-shifting.  By strategically integrating acenes into device architectures, it is possible to broaden the effective spectral coverage, minimize energy losses from unutilized photons, and significantly improve overall optoelectronic performance.  Their tunable electronic structure, combined with chemical stability and processability, further enables tailored light management strategies for next-generation adaptive optoelectronic devices