SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: Focus: Organic Solar Cells Based on Non-fullerene Acceptors: Loss Mechanism and Options for Above 20 % Efficiencies II

CPP 11.1: Invited Talk

Monday, March 27, 2023, 15:00–15:30, GÖR 226

Quantifying the potential of organic solar cells using luminescence measurements and modelling — •Jenny Nelson — Department of Physics, Imperial College London, SW7 2AZ, UK

In a molecular photovoltaic device, charge separation and energy conversion result from the evolution of a photogenerated exciton into a charge separated state, in competition with recombination to ground. Recently, new molecular materials have increased power conversion efficiency to approach 20%. To make further advances, we need to understand and isolate the effects of chemical structure, molecular packing, energetics and disorder on the competition between charge separation and recombination and hence on device efficiency. Electro- and photoluminescence have proved to be valuable tools to probe the energy and dynamics of excited states involved in photoinduced charge separation, and indirectly of the structure of molecular interfaces. Combined with other spectroscopic techniques, electrical measurements and modelling, luminescence can help us to understand how chemical and physical structure control the basic mechanisms in photovoltaic conversion. We show how such an approach can be used to study the properties and role of charge transfer states, the impact of structural and energetic disorder and to infer structure-property relationships. We apply a computational model that integrates the molecular charge transfer process with a one-dimensional drift-diffusion simulation to interpret experimental measurements and explore the effects of parameters on device performance. We consider the ultimate limits placed on solar to electric conversion by the molecular nature of the materials.