Optoelectronic characteristics of a new alternating current light emitting diode

Recently, the alternating current light emitting diode (AC LED) has been investigated and was regarded as a potential device for solid state lighting. In this study, we report a new design of the alternating current light emitting diode integrating Wheatstone Bridge (WB) circuit which has two output branches. The new type AC LED effectively increases the chip area utilization ratio to be about 70% in each bias direction, which can improve the device efficiency. Compared with the AC LED driven by DC source, the light output power of the AC LED driven by AC source was reduced by 17.8% under the input power of 1 W. Based on time resolved current and driving voltage properties, it is found that the AC LED was turned on only half the time in one cycle, which leads to the increase of driving current for the same input power. According to calculation, 79% illuminating duration of the AC LED driven by AC was higher than the driving current of AC LED operating in DC. Therefore, the serious efficiency drooping phenomenon caused by the higher driving current and injection current density results in the decline in the light output efficiency of the AC LED.