Adjusting the energy of interfacial states in organic photovoltaics for maximum efficiency

Gasparini N, Camargo FV, Frühwald S, Nagahara T, Classen A, Roland S, Wadsworth A, Gregoriou VG, Chochos CL, Neher D, Salvador M, Baran D, McCulloch I, Görling A, Lüer L, Cerullo G, Brabec C (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Nature Communications Nature Publishing Group: Nature Communications

Book Volume: 12

Article Number: 1772

Journal Issue: 1

DOI: 10.1038/s41467-021-22032-3

Abstract

A critical bottleneck for improving the performance of organic solar cells (OSC) is minimising non-radiative losses in the interfacial charge-transfer (CT) state via the formation of hybrid energetic states. This requires small energetic offsets often detrimental for high external quantum efficiency (EQE). Here, we obtain OSC with both non-radiative voltage losses (0.24 V) and photocurrent losses (EQE > 80%) simultaneously minimised. The interfacial CT states separate into free carriers with ≈40-ps time constant. We combine device and spectroscopic data to model the thermodynamics of charge separation and extraction, revealing that the relatively high performance of the devices arises from an optimal adjustment of the CT state energy, which determines how the available overall driving force is efficiently used to maximize both exciton splitting and charge separation. The model proposed is universal for donor:acceptor (D:A) with low driving forces and predicts which D:A will benefit from a morphology optimization for highly efficient OSC.

Authors with CRIS profile

Stefan Frühwald Lehrstuhl für Theoretische Chemie Andrej Classen Institute Materials for Electronics and Energy Technology (i-MEET) (i-MEET) Andreas Görling Lehrstuhl für Theoretische Chemie Larry Lüer Institute Materials for Electronics and Energy Technology (i-MEET) (i-MEET) Christoph Brabec Institute Materials for Electronics and Energy Technology (i-MEET) (i-MEET)

Involved external institutions

Istituto di Fotonica e Nanotecnologie (CNR-IFN) / Institute for photonics and nanotechnologies IT Italy (IT) Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB) King Abdullah University of Science and Technology (KAUST) / جامعة الملك عبد الله للعلوم و التقنية SA Saudi Arabia (SA) University of Oxford GB United Kingdom (GB) Advent Technologies SA GR Greece (GR) Universität Potsdam DE Germany (DE)

How to cite

APA:

Gasparini, N., Camargo, F.V., Frühwald, S., Nagahara, T., Classen, A., Roland, S.,... Brabec, C. (2021). Adjusting the energy of interfacial states in organic photovoltaics for maximum efficiency. Nature Communications, 12(1). https://doi.org/10.1038/s41467-021-22032-3

MLA:

Gasparini, Nicola, et al. "Adjusting the energy of interfacial states in organic photovoltaics for maximum efficiency." Nature Communications 12.1 (2021).

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