<p>Disclosed is an organic thin-film solar cell which has a pair of electrodes and at least one organic layer composed of at least two organic compounds sandwiched between the pair of electrodes. The difference (?Af) in the affinity level of the two main organic compounds from the at least two organic compounds mentioned above satisfies the following equation (a). 0.5 eV < ?Af < 2.0 eV (a)</p>
