Synergism between LDLB and true CD to achieve angle-dependent chiroptical inversion and switchable polarized luminescence emission in nonreciprocal nanofibrous films

Abstract

Chiroptical nanomaterials including chiralized advanced functional nanofibers have attracted ever-increasing interest in multi-disciplinary fields. Nowadays, electronic circular dichroism (CD) is the most widely used technique to evaluate chiral properties. Numerous studies have shown that the occurrence of linear dichroism and linear birefringence (LDLB) phenomenon in chiral micro-/nano-architectures makes it challenging to distinguish their inherent chiral information. However, tactfully combining LDLB with true circular dichroism (true CD) may lead to a new class of chiroptical materials. In this study, we demonstrate that transparent nanofibrous films infiltrated with poor solvents can show unique LDLB properties, which allows achiral nanofibrous films to exhibit these features regularly opposite Cotton signals by simply flipping the two faces of the same film or even rotating the testing angles of the sample around its optical axis in a single face. More importantly, we can quantitatively distinguish the contribution of LDLB from true CD in the chiral composite nanofibrous system and even effectively combine them into a single unity. This kind of adjustable flexible film material shows outstanding value in the field of optoelectronics. Its large intrinsic LDLB feature and angle-dependent, non-reciprocal transmission for polarized lights are exploited to fabricate programmable polarized light-emitting devices through the resin encapsulation process. This study may provide an easy and powerful way for the construction and implementation of novel polarization optical materials towards future intelligent optical encryption and advanced anti-counterfeiting devices.