Himpsel, F.J.3; Cook, P.L.3; de la Torre, G.4; García Lastra, Juan Maria5; Gonzalez-Moreno, R.6; Guo, J.-H.9; Hamers, R.J.3; Kronawitter, C.X.9; Johnson, P.S.3; Ortega, J.E.6; Pickup, D.6; Ragoussi, M.-E.4; Rogero, C.6; Rubio, A.6; Ruther, R.E.3; Vayssieres, L.8; Yang, W.9; Zegkinoglou, I.3
1 Atomic scale modelling and materials, Department of Energy Conversion and Storage, Technical University of Denmark2 Department of Physics, Technical University of Denmark3 University of Wisconsin-Madison4 Universidad Autónoma de Madrid5 Department of Energy Conversion and Storage, Technical University of Denmark6 Universidad del Pais Vasco7 Lawrence Berkeley National Laboratory8 Xi’an AMS Center, SKLLQG, Institute of Earth Environment9 Lawrence Berkeley National Laboratory
This overview illustrates how spectroscopy with soft X-rays can assist the development of new materials and new designs for solar cells. The starting point is the general layout of a solar cell, which consists of a light absorber sandwiched between an electron donor and an electron acceptor. There are four relevant energy levels that can be measured with a combination of X-ray absorption spectroscopy and photoelectron spectroscopy, as illustrated for an organic dye as absorber attached to a p-doped diamond film as donor. Systematic measurements of organometallic dyes (phthalocyanines and porphyrins) as a function of the metal atom are presented for the metal 2p and N 1s absorption edges. In combination with density functional theory one can discern trends that are useful for tailoring absorber molecules. A customized porphyrin molecule is investigated that combines an absorber with a donor and a linker to an oxide acceptor. The bridge to device fabrication is crossed by correlating spectroscopic features with the photocurrent in hematite photoanodes for water splitting. For speeding up the development of new materials and designs of solar cells a feedback loop between spectroscopy, theory, synthesis and device fabrication is envisioned.
Journal of Electron Spectroscopy and Related Phenomena, 2013, Vol 190, p. 2-11
Solar cell; Photovoltaics; X-ray absorption spectroscopy; Band offset; Dye molecule; Diamond