Engineering highly directional Bloch surface wave-coupled augmented emission in perovskite nanocrystals-embedded photonic crystal

Photonic crystals (PhCs) alter the emission properties of integrated emitters by modifying the local density of states, thereby controlling the spontaneous emission rate and directionality. However, the respective roles of photonic architecture and intrinsic emitter properties in determining the performance of coupled emitters under identical photonic environments remain less explored. In this work, two CsPbBr3 nanocrystals (NCs)—pristine (CPB) and Zn-alloyed CsPbBr3 (Zn-CPB), possessing 47% and 96% intrinsic quantum yields, respectively—are integrated in a one-dimensional photonic crystal (1D-PhC) to study the Bloch surface wave (BSW)-based emission enhancement and directionality. Transfer matrix method simulations were employed to optimize the PhC architecture and ensure efficient spectral overlap between the BSW resonance and the emission spectra of both emitters. Both the NCs exhibit polarized, highly directional emission (<4° angular spread) and a comparable lifetime reduction upon coupling to the BSW. Under identical excitation conditions, both emitters exhibit nearly 280-fold enhancement in 1D-PhC coupled emission. Despite experiencing comparable relative enhancement, Zn-CPB produces substantially stronger photonic crystal-coupled emission intensity owing to its higher emission efficiency and absorption cross-section. These findings establish that, while the relative photonic enhancement and Purcell factor estimated from the lifetime reduction are primarily governed by the PhC architecture, the achievable absolute directional emission intensity is strongly determined by the intrinsic emissive properties of the emitter. Consequently, comparable photonic enhancement does not necessarily translate into comparable emission intensity, highlighting the importance of considering both coupling conditions and emitter characteristics in the design of highly efficient directional light sources.