Energy ordering of singlet and triplet excited states in indacenodithiophene and indenofluorenes molecules in singlet fission: A model exact and density matrix renormalization group study

摘要

Energy ordering of lowest singlet (S-1) and triplet excited state (T-1) dominates the optoelectronic properties of conjugated molecules. The small magnitude of S-1 - T-1 (Delta E-ST) is favourable for designing efficient organic light-emitting diodes (OLEDs). Moreover, basic energy criteria E(T-1)/E(S-1) <= 0.5 ensures singlet fission (SF) process to occur enhancing the efficiency of photovoltaic devices. The low-lying singlet and triplet excited state calculations are carried out for S-indacene, indacenodithiophene derivatives and indenofluorene homologs within Pariser-Parr-Pople model Hamiltonian using exact diagonalization and Density Matrix Renormalization Group (DMRG) techniques. S-indaceno[1,2-b:5,6-b'] dithiophene, diethno-s-indaceno dithiophene, indeno[1,2-b]fluorene are found to show a significant promise in designing novel SF materials.