SOLAR CELL

PROBLEM TO BE SOLVED: To provide a solar cell superior in conversion efficiency. SOLUTION: This solar cell includes joint surfaces of at least two kinds of semiconductor materials InAlAs and Inp whose band gap energies Eg1 and Eg2 are different from each other. It adopts such a hetero structure of type II that only either of upper-end energy level EV2 of valence electron band of the other semiconductor material Inp and lower-end energy level Ex2 of conductive band thereof is between upper-end energy level Ev1 of one semiconductor material InAlAs and lower-end energy level Ec1 of valence electron thereof. In two semiconductor materials InAlAs and Inp, one material InAlAs whose lower-end energy level of conductive band is higher is doped into n-type, and the other semiconductor material Inp whose lower-end energy level of conductive band is lower is doped into p-type, and thus a solar cell 10 is constituted through the pn-type joint of both semiconductor materials InAlAs and Inp.