Internally Polarized Covalent Organic Frameworks: A Design Strategy for Single-Component Photovoltaics
Year: 2026
Type: preprint
Abstract: Molecular dipoles generate strong electric fields on the sub-nanometer scale, the very scale on which photogenerated excitons in organic semiconductors are bound. Harnessing such fields to drive charge generation throughout a photovoltaic material, however, has not been achieved. Realizing this would require ordering vast numbers of molecules throughout the bulk, which is precisely the structural control offered by covalent organic frameworks (COFs). In this work, we explore in silico the design of COFs that exploit internal-field-driven exciton dissociation, and show how they can be used to overcome a central challenge in single-component organic photovoltaics: converting strongly bound Frenkel excitons into long-lived separated charges. Using models that span from a single donor–bridge–acceptor unit to the full periodic material, we follow the photoexcitation process through its full cycle, from light absorption, through exciton dissociation, to charge recombination, and in turn isolate the effect of internal polarization at each stage. We show that polarization is essential for efficient exciton dissociation, preventing the kinetic hole trapping prevalent in an unpolarized analog. To investigate the recombination process on the nanosecond timescale, we develop a dedicated nonadiabatic molecular dynamics protocol, which, validated against an experimentally known donor–acceptor COF built from the same units, reproduces its charge-carrier lifetime with high accuracy. Applying it to the newly designed systems, we predict an almost 40-fold increase in charge-carrier lifetime. Our results identify internal polarization as a promising, unexplored approach to organic photovoltaic design and demonstrate how electronic-structure engineering at the building-block level translates into material-level performance.
Source: ChemRxiv
Authors: Miko laj Martyka, Joanna Jankowska
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221764662