On the Absence of Triplet Exciton Loss Pathways in Non-Fullerene Acceptor based Organic Solar Cells
Maria S. Kotova, Giacomo Londi, Johannes Junker, Stefanie Dietz, Alberto Privitera, Kristofer Tvingstedt, David Beljonne, Andreas Sperlich, Vladimir Dyakonov
We investigate the viability of highly efficient organic solar cells (OSCs) based on non-fullerene acceptors (NFA) by taking into consideration efficiency loss channels and stability issues caused by triplet excitons (TE) formation. OSCs based on a blend of the conjugated donor polymer PBDB-T and ITIC as acceptor were fabricated and investigated with electrical, optical and spin-sensitive methods. The spin-Hamiltonian parameters of molecular TEs and charge transfer TEs in ITIC e.g., zero-field splitting and charge distribution, were calculated by Density Functional Theory (DFT) modelling. In addition, the energetic model describing the photophysical processes in the donor-acceptor blend was derived. Spin-sensitive photoluminescence measurements prove the formation of charge transfer (CT) states in the blend and the formation of TEs in the pure materials and the blend. However, no molecular TE signal is observed in the completed devices under working conditions by spin-sensitive electrical measurements. The absence of a molecular triplet state population allows to eliminate a charge carrier loss channel and irreversible photooxidation facilitated by long-lived triplet states. These results correlate well with the high power conversion efficiency of the PBDB-T:ITIC-based OSCs and their high stability.
A Novel Thiophene-fused Ending Group Enabling an Excellent Small Molecule Acceptor for High-performance Fullerene-free Polymer Solar Cells with 11.8% Efficiency
Density-Functional Theory (DFT) and Time-Dependent DFT Study of the Chemical and Physical Origins of Key Photoproperties of End-Group Derivatives of the Nonfullerene Bulk Heterojunction Organic Solar Cell Acceptor Molecule IDIC
Tuning Domain-Based Charge Transfer in Organic Dyes: Impact of Heteroatom Doping on the $π$-Linker of Carbazole-Based Systems
Institute of Physics, Faculty of Physics, Astronomy；Informatics, Nicolaus Copernicus University in Toru\' n , Grudzi a dzka 5, 87-100 Toru\' n , Poland；Faculty of Chemistry, Nicolaus Copernicus University in Toru\' n , Grudzi a dzka 5, 87-100 Toru\' n , Poland
Getting the Right Twist: Influence of Donor-Acceptor Dihedral Angle on Exciton Kinetics and Singlet-Triplet Gap in Deep Blue Thermally Activated Delayed Fluorescence Emitter
