Relationship between Energetic Disorder and Reduced Recombination of Free Carriers in Organic Solar Cells. Issue 8 (5th January 2023)

• Record Type: Journal Article
• Authors: Hosseini, Seyed Mehrdad; Wilken, Sebastian; Sun, Bowen; Huang, Fei; Jeong, Sang Young; Woo, Han Young; Coropceanu, Veaceslav; Shoaee, Safa
• Is Part Of: Advanced energy materials. Volume 13:Issue 8(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-05
• Subjects: energetic disorder -- non‐radiaive decay -- reduced recombination; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202203576
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Reducing non‐radiative recombination is key to achieve high fill factors (FFs) in organic solar cells. While it is generally accepted that recombination proceeds via charge transfer (CT) states at the donor:acceptor interface, the underlying principles that dictate the decay kinetics of these CT states are not yet well understood. Here, a study on the effect of energetic disorder is presented. Based on a data set of 10 representative donor:acceptor blends, clear correlations between disorder, the recombination coefficient of free charge carriers, and the non‐radiative voltage loss are found. It is suggested that a narrower distribution of CT energies leads to a longer CT decay time and thus reduces non‐radiative losses. This leads to a simultaneous improvement of the FF and open circuit voltage and highlights the importance of having materials with low energetic disorder on the way to the commercialisation of organic photovoltaics. Abstract : Free charge recombination in disordered organic solar cells proceeds through the formation and decay of charge transfer states. The recombination of free carriers and the non‐radiative voltage loss is investigated, to come up with a consistent picture that energetic disorder negatively influences both recombination of free carriers and the voltage loss through the non‐radiative decay of the charge transfer state.