The invention solves issues of color purity of white color, stability of color and luminous efficiency. The disclosed diode includes substrate, Bragg reflection mirror, anode, hole transport layer, luminous layer, cavity barrier layer, electron transport layer, and cathode. Through structure of micro cavity, changing luminous characters of broadband of organic material, the invention realizes irradiance in two modes of resonance in visible range, making match of spectrum generate white light. Since luminous layer is positioned near to antinode of stationary field intensity in two modes of resonance in micro cavity, luminous intensities in two modes are enhanced, and luminous efficiency is increased. Under condition of not changing length of cavity, adjusting relative position of luminous layer changes relative luminous intensities between two modes to optimize color purity. Features are: stable white light and raised luminous efficiency.