We report the influence of organic materials on the thermal stability and emission efficiency of organic light-emitting diode (OLED). To improve the device performance several hole transporting materials and emitting materials were developed based on triphenylamine and metal-chelate complex, respectively. The electroluminescent characteristics of the OLEDs are shown and discussed in view of properties of the materials. Control of light emission in the OLED with microcavity is also presented to suggest a new application.