Field Effect versus Driving Force: Charge Generation in Small‐Molecule Organic Solar Cells. Issue 47 (9th November 2020)

• Record Type: Journal Article
• Authors: Nikolis, Vasileios C.; Dong, Yifan; Kublitski, Jonas; Benduhn, Johannes; Zheng, Xijia; Huang, Chengye; Yüzer, A. Celil; Ince, Mine; Spoltore, Donato; Durrant, James R.; Bakulin, Artem A.; Vandewal, Koen
• Is Part Of: Advanced energy materials. Volume 10:Issue 47(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-09
• Subjects: charge generation -- driving force -- field‐dependent -- organic solar cells -- ultrafast spectroscopy; 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.202002124
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Efficient charge generation in organic semiconductors usually requires an interface with an energetic gradient between an electron donor and an electron acceptor in order to dissociate the photogenerated excitons. However, single‐component organic solar cells based on chloroboron subnaphthalocyanine (SubNc) have been reported to provide considerable photocurrents despite the absence of an energy gradient at the interface with an acceptor. In this work, it is shown that this is not due to direct free carrier generation upon illumination of SubNc, but due to a field‐assisted exciton dissociation mechanism specific to the device configuration. Subsequently, the implications of this effect in bilayer organic solar cells with SubNc as the donor are demonstrated, showing that the external and internal quantum efficiencies in such cells are independent of the donor‐acceptor interface energetics. This previously unexplored mechanism results in efficient photocurrent generation even though the driving force is minimized and the open‐circuit voltage is maximized. Abstract : Field‐assisted charge generation upon illumination of neat SubNc sandwiched between charge selective electrodes is shown to be efficient, and results in low voltage losses with high quantum efficiencies. The described effects can play an important role in the current state‐of‐the‐art, high efficiency organic solar cells with low driving force for charge generation.