Optimizing External Quantum Efficiency in Scattering‐Enhanced QD Composites for Color Displays: A Rigorous Monte Carlo Approach

The efficiency of colloidal quantum dot (QD) color‐conversion films is fundamentally limited by the critical trade‐off between light extraction and parasitic self‐absorption. Although incorporating scattering particles is a standard strategy to disrupt total internal reflection (TIR) modes, empirical optimization is often constrained by the complex interplay between scattering anisotropy and optical path length extension. This paper presents a rigorous wavelength‐dependent 2D cross‐sectional Monte Carlo simulation to decouple these competing mechanisms in perovskite QD‐PMMA polymer composites embedded with TiO scatterers. By integrating Mie theory with stochastic propagation modeling, we systematically analyze the impact of TiO particle radius () and volume fraction on external quantum efficiency. Our model demonstrates the existence of an optimal scattering regime (typically at a volume fraction of 20–25%) where the out‐coupling probability is maximized before reabsorption losses dominate. Furthermore, our findings reveal that surface topology plays a decisive role; the transition from a specular to a Lambertian interface alters the optimal scattering parameters by disrupting the TIR condition more effectively than volumetric scattering alone. These findings provide a quantitative design blueprint for maximizing the luminous efficiency of next‐generation wide‐color gamut displays and micro‐LED arrays.