Spectral Dependence of Photovoltaic Cell Conversion Efficiency for Monochromatic Radiation

Abstract

Theoretical limit of solar cell conversion efficiency given by Shockley and Queisser is calculated for the case that the cell is illuminated by solar radiation. If the input radiation is monochromatic, the efficiency can exceed the limit. The aim of our study is to experimentally demonstrate this theoretical prediction and to obtain the experimental results of spectral dependence of photovoltaic cell conversion efficiency. Conversion efficiencies of two types of Si photodiodes (equivalent to solar cells) are determined through the measurements of current–voltage characteristics as a function of the wavelength and the incident radiant power. As the theory predicts, it has been confirmed that the conversion efficiency is almost proportional to the wavelength and also to the logarithm of the incident radiant power. Also, it has been experimentally confirmed that the power conversion efficiency for long wavelength monochromatic radiation is higher than that for white radiation.