Reconstruction of the charge collection probability in a solar cell from internal quantum efficiency measurements

A method is proposed to analyze the internal quantum efficiency spectra that are commonly obtained on solar cells by measuring their current response in monochromatic light as a function of wavelength. The efficiency values h are regarded as a function of the reciprocal y=1/a of the light absorption coefficient. The integral relation between h(y) and the charge collection probability distribution in the cell w(z), with a simple change of variables, can be put in the form of a convolution. A transformed version of this convolution is approximately inverted to yield an explicit expression of w(z) in terms of h(y) and its derivatives. The method is preliminarily tested on simulated data and is used to analyze published measurements obtained on a Si solar cell and a proton-irradiated InP solar cell.