Bulk versus surface charge recombination kinetics in polymer heterojunction nanoparticle photocatalyst dispersions
6 affiliations
- 1Institute of Molecular Science, University of Valencia 46980 Paterna Valencia Spain
- 2Department of Chemistry, Centre for Processable Electronics, Imperial College London London W12 0BZ UK
- 3King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC) Thuwal 23955-6900 Saudi Arabia
- 4University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry Währinger Straße 42 1090 Vienna Austria
- 5Department of Chemistry, Chemistry Research Laboratory, University of Oxford Oxford OX1 3TA UK
- 6Andlinger Center for Energy and the Environment, Department of Electrical and Computer Engineering, Princeton University Princeton NJ 08544 USA
Abstract
Organic donor–acceptor heterojunction nanoparticles have emerged as promising photocatalysts for solar hydrogen production, combining efficient light harvesting, donor–acceptor charge separation, and the generation of long-lived charge carriers. However, the identity of the charge populations responsible for photocatalytic turnover remains unresolved. Here, we study photogenerated polarons in aqueous oligo(ethylene glycol)-functionalized IDTBT:IDTBR-based heterojunction nanoparticles using transient absorption spectroscopy (TAS) and photoinduced absorption spectroscopy (PIAS) to probe, respectively, the transient polarons generated under pulsed excitation and long-lived polarons that accumulate under continuous illumination. By directly correlating spectroscopic signatures with photocatalytic hydrogen evolution, we show that the steady-state PIAS response tracks photocatalytic activity, establishing long-lived accumulated charges as the reactive population governing photocatalytic turnover. Excitation-fluence studies further demonstrate that the contrasting TAS and PIAS responses originate from distinct trapped-charge populations, with decay times at matched charge densities being five orders of magnitude faster for TAS compared to PIAS. We attribute the exceptionally long lifetimes measured in PIAS to the synergistic effects of donor–acceptor charge separation, progressive trap filling under continuous illumination, and dielectric stabilisation provided by the aqueous glycol-functionalized environment, which together suppress charge recombination and enable long-lived charge accumulation under operating conditions. These findings identify operando PIAS as a powerful approach for probing catalytically relevant charge populations and provide mechanistic design principles for engineering organic semiconductor photocatalysts with enhanced solar fuel performance.
Versions
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BibTeX
@article{gonzalezcarrero2026bulk,
title = {{Bulk versus surface charge recombination kinetics in polymer heterojunction nanoparticle photocatalyst dispersions}},
author = {Soranyel Gonzalez-Carrero and Jan Kosco and Chen Zhang and Michael Sachs and Teng Fei and Iain McCulloch and James R. Durrant},
journal = {Chemical science},
year = {2026},
month = oct,
doi = {10.1039/d6sc07200c},
url = {https://europepmc.org/article/PMC/PMC13728860},
note = {CC BY},
}
RIS
TY - JOUR
TI - Bulk versus surface charge recombination kinetics in polymer heterojunction nanoparticle photocatalyst dispersions
AU - Soranyel Gonzalez-Carrero
AU - Jan Kosco
AU - Chen Zhang
AU - Michael Sachs
AU - Teng Fei
AU - Iain McCulloch
AU - James R. Durrant
PY - 2026
DA - 2026/10/27
JO - Chemical science
DO - 10.1039/d6sc07200c
UR - https://europepmc.org/article/PMC/PMC13728860
AB - Organic donor–acceptor heterojunction nanoparticles have emerged as promising photocatalysts for solar hydrogen production, combining efficient light harvesting, donor–acceptor charge separation, and the generation of long-lived charge carriers. However, the identity of the charge populations responsible for photocatalytic turnover remains unresolved. Here, we study photogenerated polarons in aqueous oligo(ethylene glycol)-functionalized IDTBT:IDTBR-based heterojunction nanoparticles using transient absorption spectroscopy (TAS) and photoinduced absorption spectroscopy (PIAS) to probe, respectively, the transient polarons generated under pulsed excitation and long-lived polarons that accumulate under continuous illumination. By directly correlating spectroscopic signatures with photocatalytic hydrogen evolution, we show that the steady-state PIAS response tracks photocatalytic activity, establishing long-lived accumulated charges as the reactive population governing photocatalytic turnover. Excitation-fluence studies further demonstrate that the contrasting TAS and PIAS responses originate from distinct trapped-charge populations, with decay times at matched charge densities being five orders of magnitude faster for TAS compared to PIAS. We attribute the exceptionally long lifetimes measured in PIAS to the synergistic effects of donor–acceptor charge separation, progressive trap filling under continuous illumination, and dielectric stabilisation provided by the aqueous glycol-functionalized environment, which together suppress charge recombination and enable long-lived charge accumulation under operating conditions. These findings identify operando PIAS as a powerful approach for probing catalytically relevant charge populations and provide mechanistic design principles for engineering organic semiconductor photocatalysts with enhanced solar fuel performance.
SN - 2041-6520
SN - 2041-6539
ER -