Design of Low-Intensity Photovoltaic Cell to Charge Mobile Phone

In recent years, solar cell technologies have become increasingly attractive as a renewable alternative to traditional fuel energy resources. Many kinds of materials for solar cell fabrication have been developed such as a-Si, c-Si, poly-Si,GaAs, CuInGaSe, CdS, Dye-sensitive, and so on. Most of these solar cells are irradiated for outdoor to generate DC power. In this work, solar cells experience daily variation outdoor in low light intensity and indoor in weak illumination, with incident power from the sun varying between 0 and 100mW/cm2.As the light intensity decreases, the bias point and current through the cell also decreases and the equivalent resistance of the cell may approach to the shunt resistance. Therefore, considerations on photogeneration mechanism of solar cells under low level intensity should be concerned, such as irradiated light spectrum, high shunt resistance, low surface recombination, lightly doping concentration and available bandgap, for indoor low-level illumination. Although CdS cells may be a good choice, amorphous melt-grade silicon and CuInGaSe solar cells will be developed for cost and contamination requirements. In addition to weak-intensity design on the modified solar cells, it is essential importance that circuit design on photo-generated charge pump and low dropout (LDO) regulator gives sufficient power to charge Li-ion battery for cell phones and portable consumer electronics. In this research, several circuits should be implemented and integrated together to be single chip, such as charge pump and multiplier circuit, protection circuit, start-up circuit, current limiting circuit, LDO linear regulator, and output voltage monitor. So, a low dropout regulator provides a continuously regulated output voltage of 5V.

Project ID:PB10401-1106
External Project ID:MOST104-2623-E182-001-ET