Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99790

99790 - Optical Properties of Halide Perovskite in Polymer Matrices 

Hybrid organic-inorganic perovskites are an exciting class of materials with applications in solar cells, flash photomemory, and LEDs. These materials have the potential to contribute to the advancement of renewable energy and next-generation computing. With such a wide range of applications, researchers need a way to tune the perovskite crystals to fit specific uses. Previous studies have used polymers as matrices for increased crystal stability and protection from degradation by water or heat. In addition, polymers have been shown to improve the quality of/reduce the defects in the crystals, thus improving device performance. However, a fundamental study is not established yet to determine the polymer chemistry on crystal growth. Previous studies have used smaller molecules as ligands or surfactants to inhibit the crystal growth and thus control their size. Tuning the size of the crystals can lead to desired optical properties needed in specific applications. Therefore, it is proposed here that by choosing the appropriate polymers, they can act as “macroligands” that control the size of the crystal while also acting as a template for the perovskite synthesis, leading to a highly tunable and stable organic-inorganic perovskite material.

We synthesized hybrid inorganic-organic perovskite (methylammonium lead tribromide/MAPbBr3) crystals in four different polymer matrices: poly(methyl methacrylate)/PMMA, poly(ethylene oxide)/PEO, polystyrene/PS, and polyvinylpyrrolidone/PVP. Each polymer chosen had a different chemical structure in the repeat unit that affected its binding strength to the organic portion of the perovskite. The perovskite-polymer mixtures were studied as both spin-coated films and in solution. There is a drastic change in the optical properties (UV-vis absorbance and fluorescence), which is dependent on the chosen polymer. TEM images and XRD data were also analyzed to quantify crystal size. Polar polymers that strongly interact with the perovskite materials, such as PVP, control crystal growth, resulting in nanocrystals. The formation of nanocrystals was further confirmed by samples exhibiting increased fluorescence and UV absorption. 

The results presented here build a framework for selecting polymer materials that promote nanocrystal formation and control the optical properties of the materials, which is necessary for targeted applications. Knowing which polymers will yield bulk crystals and which will yield nanocrystals can lead to more informed decision-making when fabricating devices such as LEDs or solar cells, thus improving device performance. Polymer “macroligands” have the potential to be broadly expanded to include different inorganic materials, which will open new avenues for synthesizing hybrid polymer/inorganic nanocrystal materials with tunable physical properties via nanocrystal size and shape. 

Presenting Author: Lindsay Jones Pennsylvania State University

Presenting Author Biography: Lindsay is a senior undergraduate student at Penn State University. She is majoring in materials science and engineering with a concentration in polymer science and is minoring in statistics. She currently works on undergraduate research with Dr. Rob Hickey, studying interactions between organic and inorganic materials.

Authors:

Lindsay Jones Pennsylvania State University
Yifan Xu Penn State University
Robert Hickey Penn State University