Faculty Member: Prof. Rick Ubic
Recent advances in hybrid organic-inorganic ceramics have shown lead halide perovskites like (CH3NH3)PbI3 to be promising candidates for thin-film photovoltaics, allowing low-cost synthesis of solar cells. While the theoretical efficiency limit for (CH3NH3)PbI3-based devices is 28%, even the more modest values of ~20% now commonly reported put these materials in the same league as silicon PVs, which have efficiencies of 20-25% in the lab (and up to 16% in commercial systems). The perovskite is the optically-active layer in such devices, akin to the electron-donor material in heterojunction solar cells, absorbing light and injecting electrons (and holes) into conducting media. Other layers assist with charge separation; however, the charge-generation and transport properties are not yet fully understood. In addition, in order for perovskite photovoltaics to become a commercial success, two key barriers must be overcome: limited stability and environmental toxicity.
Role of Participant(s):
Solar-cell devices will be fabricated via a combination of spin coating and sputtering. Specifically, selectively etched ITO-glass substrates will be coated successively with PEDOT:PSS, spiro-OMeTAD, or NiOx; a layer of perovskite (CH3NH3)PbI3-xSCNx will be added followed by Al-doped ZnO or PCBM, and finally a metal electrode will be sputtered onto the device. The addition of Al to the n-type ZnO layer can increase both conductivity and optical transmission, and the addition of PbSCN (lead thiocyanate) to the perovskite improves the stability in ambient humidity.