Highly efficient Si-nanorods/organic hybrid core-sheath heterojunction solar cells

We report a hybrid solar cell based on well-aligned crystalline silicon nanorods (SiNRs) and an organic semiconductor, 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD), in a core-sheath heterojunction structure. The device is formed by spin coating Spiro-OMeTAD on SiNRs array fabricated by electroless chemical etching. A silver grid on a conductive poly (3,4-ethylene-dioxythiophene): polystyrenesulfonate layer is used as the top transparent anode. A power conversion efficiency of 10.3% has been obtained for a 1-cm(2) cell with 0.35-mu m long SiNRs. The high efficiency and simple solution process used suggest that such devices are promising for developing low cost and high efficiency SiNRs/organic solar cells. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3610461]