Probing the physical properties of encapsulated CsPbBr3 perovskite quantum dots thin film: A case study for enhancing stability and optoelectronic performance

Abstract

This study demonstrates the enhanced optical performance and environmental stability of CsPbBr3 perovskite quantum dots (PQDs) through polymethyl methacrylate (PMMA) surface passivation. Compared to bare CsPbBr3 quantum dots (QDs), the PMMA-capped variant exhibits superior photoluminescence with a narrow emission peak at 521 nm (FWHM: 19 nm) and high color purity (90%). Structural analyses confirm the preservation of the cubic perovskite phase and successful polymer integration without disrupting the core structure. Remarkably, PMMA–CsPbBr3 QDs retain 86% of their initial photoluminescence after 30 days in ambient conditions, far exceeding the 50% retention of CsPbBr3 QDs. Optical constants, such as the extinction coefficient, dielectric functions, and refractive index, of PMMA–CsPbBr3 QDs at key wavelengths are optimized by spectroscopic ellipsometry under a 400–1200 nm wavelength range and an incidence angle of 70°. PMMA passivation, thus, offers a scalable solution to stabilize PQDs for high-efficiency, durable light-emitting, and energy-harvesting applications.