Iron disulfide for solar energy conversion

Pyrite (Eg=0.95 eV) is being developed as a solar energy material due to its environmental compatibility and its very high light absorption coefficient. A compilationof material, electronic and interfacial chemical properties is presented, which is considered relevant for quantum energy conversion. In spite of intricate problems existing within material chemistry, high quantum efficiencies for photocurrent generation (>90%) and high photovoltages (≈500 mV) have been observed with single crystal electrodes and thin layers respectively. The most interesting aspect of this study is the use of pyrite as an ultrathin (10-20 nm) layer sandwiched between large gap p-type and n-type materials in a p-i-n like structure. Such a system, in which the pyrite layer only acts as photon absorber and mediates injection of excited electrons can be defined as sensitization solar cell. The peculiar electron transfer properties of pyrite interfaces, facilitating interfacial coordination chemical pathways, may turn out to be very helpful. Significant research challenges are discussed in the hope of attracting interest in the development of solar cells from this abundant material. © 1993.