Organic light emitting diodes (OLEDs) have advanced dramatically since they exhibit great promise in various applications such as displays, solid-state lighting, and (bio)chemical sensing. In this dissertation, multiple approaches were employed to enhance the performance of OLEDs and OLED-based sensing platforms. Comprehensive investigations were conducted on electroluminescence (EL) spikes and tails in charge trapping guest-host OLEDs and their influence on OLED-based sensor performance. Novel microstructures and device architectures were developed to construct OLED sources with spectrally selective and enhanced emission. The peak emission wavelength of the multicolor microcavity devices with MoO3 as the HIL/spacer was tunable from 493 to 639 nm. The controlled microporous structures formed by polystyrene (PS):polyethylene glycol (PEG) was able to enhance the forward light extraction of the OLED by up to ~60%. The combination of the PtOEP:PS:PEG sensing film coupled with the multicolor microcavity OLEDs and the appropriate OPD, and the possibility to combine time- and intensity-domain analyses have shed light on the opportunities to realize simple, compact, potentially disposable sensors for the detection of O2, pH and other (bio)chemical analytes and parameters.