Yellowish White-Light Emission Involving Resonant Energy Transfer in a New One-Dimensional Hybrid Material: (C9H10N2)PbCl4

The present work deals with a new one-dimensional (1D) organic-inorganic hybrid material, namely (C9H10N2)PbCl4 (abbreviated as AQPbCl(4)). Its crystal structure is built up from the infinite 1D chain of edge-sharing PbCl6 octahedra surrounded by 3-aminoquinoline (abbreviated as AQ) organic molecules. Contrary to the most organic-inorganic hybrid materials, where the organic moieties act as barriers and the inorganic parts play the role of quantum wells, both inorganic and organic parts in AQPbCl(4) are optically active, giving rise to optical properties involving the competition and the interaction of two organic and inorganic emitting entities. Under UV excitation, this hybrid compound shows a strong yellowish white-light emission that can be seen even with the naked eye and at room temperature. The photoluminescence spectrum is composed of a strong and broad yellow band at 538 nm associated with pi-pi* transition localized within the AQ organic molecule and a less intense band in the UV region at 340 nm associated with an inorganic Wannier exciton confined in the PbCl4 inorganic wires. These attributions were made possible thanks to comparisons with homologous materials, and they were supported by theoretical band structure calculations. In addition, both theoretical and experimental investigations suggest that emission involves a resonant energy transfer mechanism in which the inorganic PbCl4 wires act as donor, and the organic cations act as acceptor. Moreover, the temperature dependence study of photoluminescence led to an estimation of the binding energies of interacting excitons and showed that the energy transfer mechanism is characterized by a remarkable enhancement of the emission band intensity.