Abstract: A tandem junction photovoltaic cell has a first p-n junction with a first energy band gap, and a second p-n junction with a second energy band gap less than the first energy band gap. The junctions are separated by a quantum tunneling junction. The first p-n junction captures higher energy photons and allows lower energy photons to pass through and be captured by the second p-n junction. Quantum dots positioned within the first p-n junction promote quantum tunneling of charge carriers to increase the current generated by the first p-n junction and match the current of the second p-n junction for greater efficiency.

Abstract: A voltaic cell uses a radioactive material for energy. Energetic particles emitted by the radioactive material boost charge carriers within a semiconductor lattice into higher energy bands. Dielectric layers having quantum dots tuned by size and spacing (density) to favor particles having specific energies permit quantum mechanical tunneling of the charge carriers before they lose significant energy, are captured, or recombine. The energetic carriers tunnel to an electrical circuit, where they perform work.