Highly sensitive switching of solid-state luminescence by controlling intersystem crossing

Weijun Zhao,Qian Peng,Zijie Qiu,Zhigang Shuai,Zikai He,Huili Ma,Yongqiang Dong,Ben Zhong Tang,Yuncong Chen,Zheng Zhao,Jacky W Y Lam

doi:10.1038/s41467-018-05476-y

Abstract

The development of intelligent materials, in particular those showing the highly sensitive mechanoresponsive luminescence (MRL), is desirable but challenging. Here we report a design strategy for constructing high performance On–Off MRL materials by introducing nitrophenyl groups to molecules with aggregation-induced emission (AIE) characteristic. The on–off methodology employed is based on the control of the intersystem crossing (ISC) process. Experimental and theoretical investigations reveal that the nitrophenyl group effectively opens the nonradiative ISC channel to impart the high sensitivity and contrast On–Off behavior. On the other hand, the twisted AIE luminogen core endows enhanced reversibility and reduces the pressure required for the luminescence switching. Thin films can be readily fabricated from the designed materials to allow versatile applications in optical information recording and haptic sensing. The proposed design strategy thus provides a big step to expand the scope of the unique On–Off MRL family.

Highlights

The development of intelligent materials, in particular those showing the highly sensitive mechanoresponsive luminescence (MRL), is desirable but challenging
Few examples of On–Off MRL materials with high contrast are available in the literature and their overall performance is unsatisfactory
To realize sensitively on–off luminescence switching, the related photophysical process requires to alter dramatically in the presence of small mechanical stimulus, which is really difficult for traditional MRL materials[23,38,39]

Summary

Results

All the six luminogens recover or enhance the luminescence They exhibit bright green or yellow fluorescence as well as in thin films and in aggregates, suggesting the ISC is blocked due to morphology change (Supplementary Fig. 2 and Supplementary Table 1-2). The PXRD patterns of thermal annealed or solvent-fumed samples exhibit sharp diffraction peaks which coincide with single crystals, indicating that the amorphous powder transfers to crystalline state. Such transformation is verified by PXRD and DSC in Supplementary Fig. 10. The results suggest a promising fast responsive and reversible haptic sensor

Discussion

Embossed film b Aluminum

Methods