Encapsulation of Perovskite Nanocrystals into Macroscale Polymer Matrices: Enhanced Stability and Polarization

Abstract

Lead halide perovskites hold promise for photonic devices, due to their superior optoelectronic properties. However, their use is limited by poor stability and toxicity. We demonstrate enhanced water and light stability of high-surface-area colloidal perovskite nanocrystals by encapsulation of colloidal CsPbBr quantum dots into matched hydrophobic macroscale polymeric matrices. This is achieved by mixing the quantum dots with presynthesized high-molecular-weight polymers. We monitor the photoluminescence quantum yield of the perovskite-polymer nanocomposite films under water-soaking for the first time, finding no change even after >4 months of continuous immersion in water. Furthermore, photostability is greatly enhanced in the macroscale polymer-encapsulated nanocrystal perovskites, which sustain >10 absorption events per quantum dot prior to photodegradation, a significant threshold for potential device use. Control of the quantum dot shape in these thin-film polymer composite enables color tunability via strong quantum-confinement in nanoplates and significant room temperature polarized emission from perovskite nanowires. Not only does the high-molecular-weight polymer protect the perovskites from the environment but also no escaped lead was detected in water that was in contact with the encapsulated perovskites for months. Our ligand-passivated perovskite-macroscale polymer composites provide a robust platform for diverse photonic applications.

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals

“…33,42 The measurements in this experiment were performed with a PMMA polymer encapsulation layer coated over the isolated CsPbBr 3 NCs, which is expected to act as a hydrophobic barrier and provide protection from water. 43 Thus, photodegradation at the highest intensities is expected to be caused by the opening of new, nonradiative sites as opposed to a waterassisted surface destruction.…”

A stable lead halide perovskite nanocrystals protected by PMMA

“…S8). The average anchoring point number of polymer chain on the MAPbBr 3 NCs can be quantitatively determined by the FTIR spectra of pure PMMA, SNBP films and PLAR films [26,29,30,34]. The anchor point number of each chain in PLAR films is about twice as much as that of SNBP films (Supplementary Text S1 and Fig.…”

“…The other method to stabilize HOIPs against water is covering them with waterresistant materials including mesoporous inorganic matrices [19][20][21][22] or organic small molecules [23]. Most recently, microencapsulation of polymer was found to offer a barrier to moisture [24][25][26][27], but the methods tend to generate lead ions at the surface and the easily exfoliated coating due to the weak chemical bonds [28].…”

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…[64,86] They also tend to degrade under exposure to high temperature [52] or high-energy electron beams. To overcome these obstacles, several groups explored several solutions, such as encapsulation strategy [137,138] and surface coating method. To overcome these obstacles, several groups explored several solutions, such as encapsulation strategy [137,138] and surface coating method.…”