Covalently Bonded Pillared Layered Bromoplumbate with High Thermal Stability: High Capacitance Gain after Photoinduced Electron Transfer

Improving
the stability and photoelectric properties are current aims in the
field of inorganic–organic hybrid lead halides. In this work,
a new covalently bonded pillared layered bromoplumbate, [Pb3Br6(CV)]n, was prepared using
a photoactive zwitterion viologen, N,N′-4,4′-bipyridiniodipropionate (CV), as a ligand. It
has a high thermal stability in air and shows a remarkable increase
of capacitance after photoinduced electron transfer (PIET). The observed
dielectric switch ratio of ∼689% at 3 kHz exceeded all reported
values at room temperature for switchable dielectric materials. The
capacitance gain was derived from the redistribution of electrons
after PIET from the lead-halide layer to organic π-aggregates,
so that the activation energy of hopping polarizability was significantly
reduced.

提升无机-有机杂化卤化铅的稳定性与光电性能，是当前该领域的核心研究方向之一。本研究以光活性两性离子紫精N,N′-4,4′-联吡啶二丙酸盐（CV）为配体，合成了一种新型共价键合柱层状溴铅酸盐[Pb3Br6(CV)]n。该材料在空气中展现出优异的热稳定性，经光诱导电子转移（Photoinduced Electron Transfer, PIET）后，其电容出现显著提升。在3 kHz频率下测得的介电开关比约为689%，远超室温下已报道的所有可切换介电材料的介电开关比数值。该电容增益源于光诱导电子转移过程中，电子从卤化铅层向有机π聚集体发生重新分布，进而使得跳跃极化率的活化能显著降低。