Bio-phototherapy constitutes a safe and non-invasive medical process that has reduced side effects. However, conventional light sources such as LEDs and lasers are relatively bulky and cumbersome and, hence, their utilization was limited. To overcome this problem and to allow better application of phototherpy,1,2 we proposes to use an organic light-emitting diode (OLED) light source that is flexible and lightweight.3 This OLED light source was further improved to facilitate deep penetration into human tissues, such that it required to include low-energy loss near infrared (NIR) irradiation.4 NIR OLED was fabricated using the bottom-emitting architecture with microcavity effect and Pt(II) metal phosphor for efficient NIR photoluminescence.5 Our results show that the intensity of a specific wavelength can be amplified by applying the microcavity effect and corresponding FWHM reduced to 40~50 nm in OLED devices.