Here we report the first known integration of CMOS fabricated silicon light-emitting diodes (SiLED) with single photon avalanche diodes (SPAD) for monolithic optics-free photoluminescence lifetime sensor pixel. We show preliminary results of the photo-excitation of platinum octaethylporphyrin (PtOEP) doped polystyrene films using SiLEDs and the subsequent time-gated SPAD measurement of its photoluminescence lifetime under air, Nitrogen, and Oxygen. These sensors were fabricated in a commercially available high voltage 0.35 mu m CMOS process and thus can be dropped in alongside traditional digital and analogue circuitry; opening up new sensing modalities for miniaturised and low-cost sensing.