SOLAR CELL

摘要

The present invention provides a thin film amorphous silicon-crystalline silicon back heterojunction and back surface field device configuration for a heterojunction solar cell. The configuration is attained by the formation of heterojunctions on the back surface of crystalline silicon at low temperatures. Low temperature fabrication allows for the application of low resolution lithography and/or shadow masking processes to produce the structures. The heterojunctions and interface passivation can be formed through a variety of material compositions and deposition processes, including appropriate surface restructing techniques. The configuration achieves separation of optimization requirements for light absorption and carrier generation at the front surface on which the light is incident, and in the bulk, and charge carrier collection at the back of the device. The shadowing losses are eliminated by positioning the electrical contacts at the back thereby removing them from the path of the incident light. Back contacts need optimization only for maximum charge carrier collection without bothering about shading losses. A range of elements/alloys may be used to effect band-bending. All of the above features result in a very high efficiency solar cell. The open circuit voltage of the back heterojunction device is higher than that of an all-crystalline device. The solar cell configurations are equally amenable to crystalline silicon wafer absorber as well as thin silicon layers formed by using a variety of fabrication processes. The configurations can be used for radiovoltaic and electron-voltaic energy conversion devices.