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Photogenerated Charge Transport in Organic Electronic Materials: Experiments Confirmed by Simulations
Author(s) -
Melianas Armantas,
Kemerink Martijn
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201806004
Subject(s) - materials science , organic solar cell , thermalisation , chemical physics , organic electronics , charge (physics) , quantum tunnelling , non equilibrium thermodynamics , organic semiconductor , range (aeronautics) , nanotechnology , charge carrier , fullerene , polymer , optoelectronics , physics , atomic physics , thermodynamics , transistor , voltage , quantum mechanics , composite material
The performance of organic optoelectronic devices, such as organic photovoltaic (OPV) cells, is to a large extent dictated by their ability to transport the photogenerated charge, with relevant processes spanning a wide temporal (fs–µs) and spatial (1–100 nm) range. However, time‐resolved techniques can access only a limited temporal window, and often contradict steady‐state measurements. Here, commonly employed steady‐state and time‐resolved techniques are unified over an exceptionally wide temporal range (fs–µs) in a consistent physical picture. Experimental evidence confirmed by numerical simulations shows that, although various techniques probe different time scales, they are mutually consistent as they probe the same physical mechanisms governing charge motion in disordered media—carrier hopping and thermalization in a disorder‐broadened density of states (DOS). The generality of this framework is highlighted by time‐resolved experimental data obtained on polymer:fullerene, polymer:polymer, and small‐molecule blends with varying morphology, including recent experiments revealing that low donor content OPV devices operate by long‐range hole tunneling between non‐nearest‐neighbor molecules. The importance of nonequilibrium processes in organic electronic materials is reviewed, with a particular focus on experimental data and understanding charge transport physics in terms of material DOS.