Colloidal semiconductor nanocrystals (NCs) are an efficient and cost-effective class of nanomaterials for optoelectronic applications. Advancements in NC-based optoelectronic devices have resulted from progress in synthetic chemistry, adjustable surface properties, and optimized device architectures. Semiconductor nanoplatelets (NPLs) stand out among other NCs due to their precise growth control, yielding uniform thickness with submonolayer roughness. In this study, we demonstrate the versatility of core/shell Cd_xHg_1-xSe/Zn_yCd_1-yS NPLs for optoelectronic applications in the short-wave infrared (SWIR) spectral range. We employed the very same core/shell NPLs for the fabrication of light-emitting diodes and photodetectors alike, achieving significant performance in both electroluminescence (external quantum efficiency ranging from 7.5% at 1280 nm to 3.8% at 1550 nm) and detection (responsivity of 0.24 A W^-1 at 1200 nm).