The utilization of MHPs in optoelectronics has surged over the past decade due to their favorable properties such as direct band gaps, a large JDOS near the band edge resulting in strong optical absorption, and high defect tolerance allowing operation close to the radiative limit. These attributes, along with easy material processing and high carrier mobilities, have enabled PCEs exceeding 26% in PSCs and EQEs over 28% in PeLEDs. Additionally, the band gap tunability of MHPs makes them suitable for multi-junction solar cells, with top devices achieving PCEs above 33%. MHPs' ability to operate near the radiative limit makes them highly luminescent, beneficial for light-emitting applications like PeLEDs and intricately linked to photovoltaic performance through optical and optoelectronic reciprocity. Understanding luminescence processes is crucial for material characterization and designing high-performance devices. However, modeling these processes is challenging due to MHPs' unique light-matter coupling, which leads to substantial self-absorption and photon recycling. This recycling, an iterative process of reabsorption and reemission, significantly impacts luminescence signals and the optoelectronic performance of PSCs and PeLEDs. In multi-junction solar cells, luminescent coupling further affects device operation. An effective model must consider both emission and absorption equally, addressing the entire range of optical modes. The thin-film nature of MHP-based devices requires a coherent wave-optical treatment, complicating the modeling due to diverging emission power issues in absorbing media. Modern devices combine thin-film and optically thick structures, necessitating a multi-scale optical framework that couples coherent and incoherent light propagation. Additionally, a model must integrate electronic transport and maintain compatibility with reciprocity relations for physical consistency. This thesis develops an optoelectronic multi-scale model to describe the behavior of PSCs and PeLEDs, incorporating photon recycling effects. A novel dipole emission model using a dyadic Green's function approach is derived where unphysical divergences in dipole emission power are eliminated. From this Green's function, emission rates, reabsorption rates, and energy fluxes are derived. The coherent model is then coupled to a net-radiation model for incoherent light intensities, applicable to optically thick layers, ensuring accurate bidirectional coupling. The net-radiation model is extended to handle microstructured scattering interfaces, describing complex light interactions. The electrical model builds on an existing drift-diffusion-Poisson implementation, with implemented extensions such as impact ionization, trapping dynamics, trap-assisted interface recombination, and boundary conditions for simulating PL experiments. The modeling framework is applied to various optoelectronic devices, examining the effects of photon recycling on photoluminescence signals in perovskite slabs and PSCs. The influence of photon recycling on current-voltage characteristics and reabsorption quantum efficiencies in PSCs is analyzed. For PeLEDs, photon recycling's impact on external quantum efficiency is assessed, including the effects of scattering structures. Finally, a perovskite-silicon tandem is analyzed to quantify the roles of photon recycling and luminescent coupling, introducing the concept of luminescent self-coupling.