Continuous production of stable chiral perovskite nanocrystals in electrospinning nanofibers to exhibit circularly polarized luminescence

Abstract

Methods allowing the facile synthesis of chiral nanomaterials with interesting chiroptical properties are highly desirable. Herein, guided by fiber-spinning chemistry (FSC), we develop a one-step strategy enabling continuous production of stable chiral perovskite nanocrystals (PNCs) with high photoluminescence (PL) quantum yields (QYs) and circularly polarized luminescence (CPL). The FSC process uses spinning nanofibers of polyacrylonitrile (PAN) as reactors for in situ generation of chiral methylammonium lead bromine (MAPbBr₃) PNCs tailored with R-(+)-methylbenzylammonium bromide (R-MBABr) or (S)-(−)-methylbenzylammonium bromide (S-MBABr). The resultant R(S)-MBABr-modified MAPbBr₃ PNCs/PAN nanofiber films, referred to as R(S)-PNCs/PAN nanofiber films, show green fluorescence with a high PL QY of up to 88%, and preserve a PL QY of 60% after storage in the atmosphere for 180 days (vs. complete fluorescence quenching in 1 day in air for pristine R(S)-PNCs). Significantly, these nanofiber films exhibit circular dichroism (CD) and circularly polarized luminescence (CPL) with dissymmetry factor (g_lum) values of 10⁻³ at room temperature. Structural and optical characterization results confirm that R(S)-MBABr passivates the surface defects of MAPbBr₃ PNCs to highly enhance the PL QY, and guarantees chirality transfer into PNCs to cause chiroptical features of CD and CPL, while the PAN nanofiber encapsulation greatly improves the PL stability of chiral PNCs. The R(S)-PNCs/PAN nanofiber films with excellent optical properties and stability are potential candidates for various optoelectronic applications.