TY - JOUR

T1 - Mode of action of the third component in ternary organic photovoltaic blend PBDB-T/ITIC:PC70BM revealed by EPR spectroscopy

AU - Popov, A. A.

AU - Uvarov, M. N.

AU - Kulik, L. V.

N1 - Funding Information: This work was supported by RFBR grant No 19-03-00149a and by state assignment to Voevodsky Institute of Chemical Kinetics and Combustion SB RAS , number AAAA-A21-121011390038-1 . Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/7

Y1 - 2021/7

N2 - Light-induced EPR (LEPR) and out-of-phase electron spin echo (ESE) techniques were applied to trace the difference of charge generation and recombination processes between highly efficient ternary OPV blend PBDB-T/ITIC:PC70BM and the corresponding binary blends PBDB-T/ITIC and PBDB-T/PC70BM. The average charge trap depth measured from LEPR decay traces decreases in the series PBDB-T/ITIC, PBDB-T/PC70BM, PBDB-T/ITIC:PC70BM. As it is evident from the out-of-phase ESE, the initial electron-hole distance within the charge-transfer state upon its formation increases in this series. The former effect facilitates charge transport, in accordance with increase of the electron mobility for the ternary blend revealed previously. The latter effect leads to reduced geminate recombination. Both effects are suggested to improve the power conversion efficiency of the ternary blends. Presumably, they originate from modification of the PBDB-T/ITIC blend morphology by addition of small amount of PC70BM.

AB - Light-induced EPR (LEPR) and out-of-phase electron spin echo (ESE) techniques were applied to trace the difference of charge generation and recombination processes between highly efficient ternary OPV blend PBDB-T/ITIC:PC70BM and the corresponding binary blends PBDB-T/ITIC and PBDB-T/PC70BM. The average charge trap depth measured from LEPR decay traces decreases in the series PBDB-T/ITIC, PBDB-T/PC70BM, PBDB-T/ITIC:PC70BM. As it is evident from the out-of-phase ESE, the initial electron-hole distance within the charge-transfer state upon its formation increases in this series. The former effect facilitates charge transport, in accordance with increase of the electron mobility for the ternary blend revealed previously. The latter effect leads to reduced geminate recombination. Both effects are suggested to improve the power conversion efficiency of the ternary blends. Presumably, they originate from modification of the PBDB-T/ITIC blend morphology by addition of small amount of PC70BM.

KW - Charge-transfer state

KW - Energetic disorder

KW - EPR spectroscopy

KW - Organic photovoltaics

KW - Recombination

KW - Ternary blend

UR - http://www.scopus.com/inward/record.url?scp=85107139872&partnerID=8YFLogxK

U2 - 10.1016/j.synthmet.2021.116783

DO - 10.1016/j.synthmet.2021.116783

M3 - Article

AN - SCOPUS:85107139872

VL - 277

JO - Synthetic Metals

JF - Synthetic Metals

SN - 0379-6779

M1 - 116783

ER -