E. Hernández

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Publications (2)0 Total impact

  • Conference Proceeding: Advances in quantum dot intermediate band solar cells
    E. Antolin, A. Martí, P.G. Linares, I. Ramiro, E. Hernández, C.D. Farmer, C.R. Stanley, A. Luque
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    ABSTRACT: Several groups have reported on intermediate band solar cells (IBSC) fabricated with InAs/GaAs quantum dots (QD) which exhibit quantum efficiencies (QE) for sub-bandgap photon energies. However, this QE is produced by the absorption of photons only through valence band (VB) to intermediate band (IB) transitions. The absorption of photons of that energy in IB to conduction band (CB) transitions is weak and is usually replaced by carrier escape. This mechanism is incompatible with the preservation of the output voltage, and therefore, it cannot lead to the high efficiencies predicted by the IBSC model. In this work, we discuss the contribution of thermal and tunneling mechanisms to IB-CB carrier escape in current QD-IBSCs. It is experimentally demonstrated that in QD-IBSC prototypes where tunnel escape has been eliminated, the sub-bandgap QE is suppressed at sufficiently low temperatures, and when this occurs, the only limit for the open-circuit voltage (V<sub>OC</sub>) is the fundamental semiconductor bandgap, as stated by the IBSC theoretical model.
    Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE; 07/2010
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    Conference Proceeding: Hot carrier solar cells: Challenges and recent progress
    M.A. Green, G. Conibeer, D. König, S. Shrestha, Shujuan Huang, P. Aliberti, L. Treiber, R. Patterson, B.P. Veettil, A. Hsieh, [......], E. Antolin, D.F. Marrón, C. Tablero, E. Hernández, J.-F. Guillemoles, L. Huang, A. Le Bris, T. Schmidt, R. Clady, M. Tayebjee
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    ABSTRACT: The limiting efficiency on the conversion efficiency of terrestrial global sunlight is not circa 31%, as commonly assumed, but 74%. To reach the lowest possible costs and hence to attain its intrinsic potential as a major source of future sustainable energy supplies, it would appear photovoltaics has to evolve to devices targeting the latter efficiency rather than the former. The hot carrier solar cell, although presenting substantial device challenges, is arguably the highest efficiency photovoltaic device concept yet suggested and hence worthy of efforts to investigate its practicality. Challenges in the implementation of hot carrier cells are identified and progress in overcoming these are discussed.
    Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE; 07/2010
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