TY - JOUR
T1 - Fate of Low-Lying Charge-Transfer Excited States in a Donor:Acceptor Blend with a Large Energy Offset
AU - Londi, Giacomo
AU - Khan, Saeed Uz Zaman
AU - Muccioli, Luca
AU - D'Avino, Gabriele
AU - Rand, Barry P.
AU - Beljonne, David
N1 - Funding Information:
This study received funding from the European Union’s Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant Agreement 722651 (SEPOMO project) and from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement 646176 (EXTMOS). L.M. thanks MIUR for financial support through PRIN Project 2015XJA9NT “Molecular Organization in Organic Thin Films via Computer Simulation of their Fabrication Processes”. Computational resources were provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S.-FNRS) under Grant 2.5020.11, as well as the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles, infrastructure funded by the Walloon Region under Grant Agreement 1117545. G.L., L.M., G.D., and D.B. gratefully thank Xavier Blase for fruitful discussions on many-body perturbation theory and for sharing the FIESTA code. D.B. is a FNRS Research Director. S.-U.-Z.K. and B.P.R. acknowledge the U.S. Department of Energy, Office of Basic Energy Sciences, for Award DE-SC0012458.
Publisher Copyright:
©
PY - 2020/12/3
Y1 - 2020/12/3
N2 - In an effort to gain a comprehensive picture of the interfacial states in bulk heterojunction solar cells, we provide a combined experimental-theoretical analysis of the energetics and dynamics of low-lying electronic charge-transfer (CT) states in donor:acceptor blends with a large frontier orbital energy offset. By varying the blend composition and temperature, we unravel the static and dynamic contributions to the disordered density of states (DOS) of the CT-state manifold and assess their recombination to the ground state. Namely, we find that static disorder (conformational and electrostatic) shapes the CT DOS and that fast nonradiative recombination crops the low-energy tail of the distribution probed by external quantum efficiency (EQE) measurements (thereby largely contributing to voltage losses). Our results then question the standard practice of extracting microscopic parameters such as exciton energy and energetic disorder from EQE.
AB - In an effort to gain a comprehensive picture of the interfacial states in bulk heterojunction solar cells, we provide a combined experimental-theoretical analysis of the energetics and dynamics of low-lying electronic charge-transfer (CT) states in donor:acceptor blends with a large frontier orbital energy offset. By varying the blend composition and temperature, we unravel the static and dynamic contributions to the disordered density of states (DOS) of the CT-state manifold and assess their recombination to the ground state. Namely, we find that static disorder (conformational and electrostatic) shapes the CT DOS and that fast nonradiative recombination crops the low-energy tail of the distribution probed by external quantum efficiency (EQE) measurements (thereby largely contributing to voltage losses). Our results then question the standard practice of extracting microscopic parameters such as exciton energy and energetic disorder from EQE.
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U2 - 10.1021/acs.jpclett.0c02858
DO - 10.1021/acs.jpclett.0c02858
M3 - Article
C2 - 33206537
AN - SCOPUS:85096522339
SN - 1948-7185
VL - 11
SP - 10219
EP - 10226
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 23
ER -