| 초록 |
Flexible solar photovoltaic devices offer a convenient alternative energy source for indoor and outdoor applications. Besides being flexible and thus easily integrated with elements of various shapes and sizes for the design of innovative energy-generating products, these unbreakable flexible modules are lightweight and suitable for applications where weight is important. Especially, the flexible Cu(In,Ga)Se2 (CIGS) thin-film solar cells have been the subject of extensive research and development since they are lightweight and durable, which make them ideal for portable-power and satellite applications. The roll-to-roll deposition process of flexible CIGS solar cells can also reduce the production cost significantly. Substrates typically used for flexible solar cells are metal or polyimide foils. However, there have been two major issues for flexible CIGS thin-film solar cells. One is the Na supply. It is well known that a small amount of Na incorporated into the polycrystalline CIGS absorber layers increases the efficiencies significantly. For solar cells on soda-lime glass substrates, Na is incorporated into CIGS during growth by diffusion from the substrates through the Mo back contact. Since metal and polyimide foils do not contain Na, the external Na elements should be supplied. The other issue with flexible CIGS solar cells is the dielectric layer for diffusion barrier and electrical isolation of each cell. The impurities in the substrates penetrated into the CIGS layer during the high temperature process and degraded the photovoltaic performance. The thin-film layers have been considered as the diffusion barrier. In this presentation, the advantages and technological issues of CIGS solar cells on flexible substrates are discussed. |
