Colloidal quantum dot (QD) color-conversion films for next-generation micro-LED and wide-color-gamut displays face a fundamental photonic bottleneck; even when the intrinsic photoluminescence quantum yield approaches unity, roughly 80% of generated photons remain trapped within the film stack due to total internal reflection (TIR) at the high-index composite/air interface. Embedding TiO₂ scattering particles is a standard industrial strategy to disrupt TIR and extend the pump optical path length, but the competing effects of scattering anisotropy, reabsorption, and surface morphology make empirical optimization slow and unreliable.

We present a wavelength-dependent 2D Monte Carlo ray-tracing simulation that decouples these competing mechanisms in perovskite QD/PMMA composites embedded with TiO₂ scatterers. The model integrates full Mie theory (via miepython), Maxwell-Garnett effective medium theory for the QD-loaded matrix, and a dependent-scattering correction for dense particle ensembles, going beyond the commonly used Henyey-Greenstein approximation, which systematically misses coherent backscattering resonances critical to accurate efficiency prediction.

Three quantitative findings emerge. First, TiO₂ particles with radius ~100 nm yield a 3-fold enhancement in average pump absorption path length (512 nm to 1552 nm) and increase total pump absorption by 76.3% in the low-concentration regime, converting an otherwise optically transparent 1 µm film into an efficient absorber without increasing QD loading. Second, the same scatterers suppress parasitic photon recycling: in high-concentration films the reabsorption rate falls from 101.5% to 23% upon introducing scatterers at optimal loading, simultaneously boosting extraction efficiency and preserving the emission color point. We confirm this spectral stabilization experimentally via angle-resolved PL measurements on FAPbBr₃/PMMA/TiO₂ films, which show negligible spectral redshift out to 70° viewing angle. Third, the simulation reveals a critical role for surface topology: while volumetric scattering alone eliminates waveguide side-losses above 2% volume fraction, specular films hit a hard limit (~16.8% top EQE) set by pump back-scattering. Coupling a Lambertian top surface with a TiO₂ volume fraction of 20% pushes top EQE to 19.6%, a relative gain of 16.7%, while simultaneously broadening the process window so that >90% of peak performance is maintained over a wide range of scatterer concentrations.

These results provide a quantitative design blueprint, optimal TiO₂ radius, volume fraction, and surface texture, for scalable, chromatically stable QD color-conversion architectures for display applications.