Key factors limiting the open circuit voltage of n/sup +/pp/sup +/ indium phosphide solar cells

Abstract

The problem of the presently obtained best open-circuit voltage (V/sub oc/) values of n/sup +/pp/sup +/ InP solar cells being considerably smaller than those predicted by basic theory is theoretically investigated. The values of some key parameters in the cells are obtained with a computer model by closely matching theoretical and measured curves for illuminated I-V, log I/sub sc/-V/sub oc/, and spectral response characteristics of a high-efficiency (17.9%) InP solar cell made by the Spire Corporation. An optimally designed InP solar cell with nearly the best efficiency that it is capable of providing in the n/sup +/pp/sup +/ shallow homojunction structure is described and modeled using these parameters. The performance parameters of the optimally designed solar cell are calculated, and it is shown that such a cell is capable of having an efficiency of 22.61% under 1 AM0 at 27 degrees C (300 K). Using a baseline solar cell design which is a slightly modified and improved version of the Spire 6 cell, the key factors which limit the open-circuit voltage V/sub oc/ of such a solar cell are discussed.<>