Quantum Dots Mediate Interface Tuning in Pseudo-Planar LBL-Assembled Ternary OPVs

Enas Moustafa^a^,^b, Stanly A Cazaly^c, Harry Bridge^d, Jolanda S Müller^a, Jun Yan^e, Stoichko Dimitrov^f, Thomas J Macdonald^d, Flurin D Eisner^c, Jenny Nelson^a

^aDepartment of Physics, Imperial College London, London SW7 2AZ, UK

^bRenewable Energy Science and Engineering Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Egypt

^cSchool of Engineering and Materials Science, Queen Mary University of London, London, UK.

^dDepartment of Electronic & Electrical Engineering, University College London

^eSchool of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, P.R. China.

^fDepartment of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, UK

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Poster, Enas Moustafa, 163
Publication date: 11th March 2026

Organic photovoltaic (OPV) devices have achieved high efficiency, but further progress is constrained by interfacial recombination and sub-optimal morphology, and limited stability. Here, we address these challenges by introducing CsPbI₃ perovskite quantum dots (PQDs) as an interlayer at the D18/Y6 interface, deposited via an orthogonal-solvent layer-by-layer process. Incorporation of an optimized PQDs interlayer boosts the power conversion efficiency from 16.7% in the binary device to 18.8% in the ternary architecture, corresponding to a relative increase of ~12%. The systematic comparative study of morphology, optical/optoelectronic and electrical characteristics, as well as the related charge recombination and transfer dynamics, revealed that the D18/PQDsY6 assembly provided a unique electronic structure that passivates PQDs surface defects and mitigates interdiffusion of the organic layers, enabling improved microstructure regulation, leading to enhanced fill factor. Moreover, the high dielectric constant of the PQDs appears to facilitate exciton dissociation at the D18/Y6 interface, allowing the PQDs to act as a relay that separates and stabilizes charges at the D18/PQDs/Y6 junction, thereby reducing the trap-assisted recombination. This leads to suppressed non-radiative recombination losses, resulting in higher open-circuit voltage (V_OC) and short-circuit current (J_SC). Beyond performance gains, the PQDs interlayer also improves the shelf-life stability under N₂, prolonging the stability for the pristine devices over 12 months. Hence, our findings demonstrate that introducing CsPbI₃ PQDs interlayer, implemented via orthogonal-solvent LBL processing, provides an effective route to tune interfacial morphology and energetics, offering a practical strategy to further enhance both efficiency and stability in OPV devices.

Acknowledgements:

E. M. acknowledges the Iberdrola Foundation under Marie Skłodowska-Curie-MSCA-COFUND, funding from the European Union's Horizon 2020 research and innovation program, Grant Agreement No 101034297 for awarding the Energy for Future-E4F-postdoctoral individual fellowship program 2024-2025.

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