Azulene

Abstract: Azulene was found to fluoresce with a frequency corresponding to transition from the second excited singlet level to the ground state. No phosphorescence was observed. No emission corresponding to transition from the lowest excited singlet to the ground state was observed. These phenomena are discussed.

Abstract: Two-dimensionally expanded π-systems, consisting of partially oxygen-bridged triarylamine skeletons that are connected to an azulene (1–3) or biphenyl core (4), were synthesized and characterized. When tetra-substituted azulene 1 was used as a hole-transporting material (HTM) in perovskite solar cells, the observed performance (power conversion efficiency = 16.5%) was found to be superior to that of the current HTM standard Spiro-OMeTAD. A comparison of the hole mobility, the ability to control the HOMO and LUMO levels, and the hole-collection efficiency at the perovskite/HTM interface in 1 with reference compounds (2–4 and Spiro-OMeTAD) led to the elucidation of key factors required for HTMs to act efficiently in perovskite solar cells.

Abstract: The dipole moments of fulvene and azulene have been calculated theoretically by the LCAO MO method, and have been obtained from experimental data. The experimental results support the theoretical predictions.