Tianyang Wang

Ambipolar organic semiconductors with cascades of energy levels for generating long-lived charge separated states: a donor–acceptor1–acceptor2 architectural triarylamine dye

A donor–acceptor1–acceptor2 architectural 4-styryltriphenyl amine-based organic semiconductor was synthesized for solar cell applications. Sequential electron transfers together with effective hole transfer lead to a charge separated state lifetime of 650 ns, therefore boosting the short circuit current and efficiency of single layer organic photovoltaic cells.

Tuning photophysical properties via alkoxyl groups in charge-separated triphenylamine sensitizers for dye-sensitized solar cells

Abstract Two charge-separated (CS) sensitizers ( MoTPA-Pyc and OcTPA-Pyc ) with methoxyl or octyloxyl groups attached to the para position of the triphenylamine donor moiety were synthesized to investigate the effect of the alkoxyl groups on the photophysical properties of the CS sensitizers and photovoltaic performances of the corresponding dye-sensitized solar cells (DSSCs). The introduction of alkoxyl groups can increase the energy gap between LUMO+1 and LUMO, leading to an increased intramolecular photo-induced electron transfer (PET) efficiency. Both MoTPA-Pyc and OcTPA-Pyc show elongated lifetimes for their CS states, resulting in an enhanced internal quantum efficiency (IQE) of DSSCs. It has been demonstrated that intramolecular PET is the key step for efficient DSSCs due to the presence of long-lived CS states allowing efficient and fast interfacial electron transfer from the CS sensitizers to the TiO 2 nanoparticles. The best efficiency of 5.76% was achieved by the MoTPA-Pyc based DSSC through a combined contribution of high IQE and efficient light harvesting. The results suggest that enhancing the intramolecular PET efficiency and the light harvesting ability of the dye-loaded TiO 2 film are effective strategies for achieving higher photovoltaic performance for CS sensitizer-based DSSCs.

Facile Synthesis of [1,2,4]Triazolo[4,3-a]pyrazin-3-amines via Oxidative Cyclization of 1-(Pyrazin-2-yl)guanidine Derivatives

In this study, we applied a novel, mild, and convenient synthetic method involving the oxidative cyclization of 1-(pyrazin-2-yl)guanidine derivatives to produce [1,2,4]triazolo[4,3-a]pyrazin-3-amines. We optimized the reaction procedure to easily obtain 5-chloro-[1,2,4]triazolo[4,3-a]pyrazin-3-amine. Various types of halogenated pyrazines can successfully undergo this process. We synthesized a series of 1-(pyrazin-2-yl)guanidines and [1,2,4]triazolo[4,3-a]pyrazin-3-amines, and then elucidated their structures based on their 1H-NMR, 13C-NMR, ESI-HRMS, and nuclear Overhauser effect spectra.