Ultrafast charge dynamics of diketopyrrolopyrrole-based terpolymers for optoelectronic applications: impact of acceptor concentrations and thermal annealing

Nchinda LT, Genene Z, Mammo W, Tegegne NA, Guldi DM, Krüger TP (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Nanoscale Royal Society of Chemistry

DOI: 10.1039/d6nr00012f

Abstract

Diketopyrrolopyrrole (DPP)-based terpolymers have emerged as promising donor materials for organic solar cells (OSCs), offering tunable optoelectronic properties, broadband absorption, and enhanced morphological stability through random terpolymerization strategies. This study investigates the ultrafast charge carrier dynamics of three DPP-based terpolymers, (P1–P3), incorporating different ratios of fluorobenzotriazole (FTAZ) and thienothiophene-capped DPP (TTDPP) acceptors. Using femtosecond transient absorption spectroscopy, we examine how acceptor ratios and thermal annealing influence photophysical processes in pristine terpolymers and their bulk heterojunction blends with PC71BM. Increasing the TTDPP content enhances backbone planarity, π–π stacking, and charge delocalization, thereby reducing recombination losses and promoting efficient charge separation. Compared to P2 and P3, the P1 terpolymer, with the highest TTDPP ratio, exhibits the most favorable intramolecular charge transfer kinetics and balanced carrier mobilities, consistent with its superior photovoltaic performance. Thermal annealing, however, reduces long-lived charge populations in all blends due to fullerene aggregation, which diminishes phase separation. These findings highlight how rational tuning of acceptor ratios in DPP-based terpolymers provides a pathway toward optimizing both efficiency and stability in OSCs.

Involved external institutions

Chalmers University of Technology / Chalmers tekniska högskola SE Sweden (SE) Addis Ababa University (AAU) ET Ethiopia (ET) University of Pretoria ZA South Africa (ZA)

How to cite

APA:

Nchinda, L.T., Genene, Z., Mammo, W., Tegegne, N.A., Guldi, D.M., & Krüger, T.P. (2026). Ultrafast charge dynamics of diketopyrrolopyrrole-based terpolymers for optoelectronic applications: impact of acceptor concentrations and thermal annealing. Nanoscale. https://doi.org/10.1039/d6nr00012f

MLA:

Nchinda, Leonato Tambua, et al. "Ultrafast charge dynamics of diketopyrrolopyrrole-based terpolymers for optoelectronic applications: impact of acceptor concentrations and thermal annealing." Nanoscale (2026).

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