Luminaires and luminaire components are provided that may include emissive, index-matching, and/or outcoupling components that are replaceable separately from other components of the luminaire. In some embodiments, an index-matching component may include a gel sheet or pad that can be disposed between an emissive component and an outcoupling component. The index-matching component may be replaceable separately from the emissive and outcoupling components. In some embodiments, an emissive component including an OLED panel and/or an index-matching component may be replaceable separately from other components of the luminaire.