Stable self-trapped broadband emission from an organolead halide coordination polymer with strong layer corrugation and high chemical robustness

Abstract

Layered organolead halides are an emerging class of self-trapped emitters, in which the unique corrugated structures are critical to afford out-of-plane distortions for self-trapping. However, the labile corner halide species are often more exposed in corrugated layers, posing the trade-off relationship between structural corrugation and chemical robustness. Herein, we report a layered architecture consisting of inorganic [Pb₂Cl₂]²⁺ slabs and interlamellar 4,5-imidazoledicarboxylate struts, exhibiting large Stokes-shifted broadband emission originating from self-trapped excitons. The coordination-assembly hybrid possesses both high structural integrity and heavily corrugated lead chloride layers, therefore affording ultrastable and efficient self-trapped photoluminescence. The broadband emission is well retained after a variety of chemical treatments and maintains the spectral profile for at least 168 h upon continuous UV irradiation under ambient conditions, superior to conventional ionic structures for halide perovskites. The photophysical carrier dynamics and the exciton self-trapping process of our layered material have been clarified by a variety of photophysical studies including ultrafast transient absorption spectroscopy.