The effect of the order-disorder transition on the band gap of kesterite Cu2ZnSnS4, an interestin... more The effect of the order-disorder transition on the band gap of kesterite Cu2ZnSnS4, an interesting material for solar cells, has been investigated by optical spectroscopy. The band gap energy (Eg) decreases continuously with increasing annealing temperature, Ta, and reaches its minimum at Ta 273 C. Eg is about 200 meV higher in the most ordered state, than in the fully disordered state. Its value and the transition kinetic depend on the sample stoichiometry. A simplified model able to explain the order degree and stoichiometry effects on the Eg value is developed. Ordering results in narrower Raman peaks without affecting the shape of the photoluminescence spectrum— except for the change in Eg—or the characteristic energy of the exponential tail below the fundamental absorption edge. Although a prolonged annealing increases the order degree, the material properties are still influenced by residual disorder as well as by defects related to the off-stoichiometry composition.
The {ital J}-{ital V} characteristics of {ital p}-{ital i}-{ital n} solar cells in the dark have ... more The {ital J}-{ital V} characteristics of {ital p}-{ital i}-{ital n} solar cells in the dark have been simulated by solving numerically the full set of transport equations. We have analyzed the dependence of dark current on the density of gap states in the intrinsic layer and on the presence of interface states between the {ital p} and {ital i} layers.
E’ descritto un flussimetro per la misura dell’intensità e distribuzione della radiazione solare ... more E’ descritto un flussimetro per la misura dell’intensità e distribuzione della radiazione solare concentrata negli impianti termodinamici di tipo “parabolic trough”. Il sensore ha la forma di un collare e viene fissato sulla superficie esterna del tubo di vetro che protegge il ricevitore cilindrico attraversato dal fluido termovettore. Il sensore è realizzato con una molteplicità di celle solari a concentrazione calibrate, da cui il termine “collare fotovoltaico”, distribuite su un piano trasversale all’asse ottico del concentratore. Dalle misure di fotocorrente e temperatura delle celle solari si ricava l’intensità e la distribuzione della radiazione solare incidente in prossimità del tubo ricevitore.
The effect of the order-disorder transition on the band gap of kesterite Cu2ZnSnS4, an interestin... more The effect of the order-disorder transition on the band gap of kesterite Cu2ZnSnS4, an interesting material for solar cells, has been investigated by optical spectroscopy. The band gap energy (Eg) decreases continuously with increasing annealing temperature, Ta, and reaches its minimum at Ta 273 C. Eg is about 200 meV higher in the most ordered state, than in the fully disordered state. Its value and the transition kinetic depend on the sample stoichiometry. A simplified model able to explain the order degree and stoichiometry effects on the Eg value is developed. Ordering results in narrower Raman peaks without affecting the shape of the photoluminescence spectrum— except for the change in Eg—or the characteristic energy of the exponential tail below the fundamental absorption edge. Although a prolonged annealing increases the order degree, the material properties are still influenced by residual disorder as well as by defects related to the off-stoichiometry composition.
The {ital J}-{ital V} characteristics of {ital p}-{ital i}-{ital n} solar cells in the dark have ... more The {ital J}-{ital V} characteristics of {ital p}-{ital i}-{ital n} solar cells in the dark have been simulated by solving numerically the full set of transport equations. We have analyzed the dependence of dark current on the density of gap states in the intrinsic layer and on the presence of interface states between the {ital p} and {ital i} layers.
E’ descritto un flussimetro per la misura dell’intensità e distribuzione della radiazione solare ... more E’ descritto un flussimetro per la misura dell’intensità e distribuzione della radiazione solare concentrata negli impianti termodinamici di tipo “parabolic trough”. Il sensore ha la forma di un collare e viene fissato sulla superficie esterna del tubo di vetro che protegge il ricevitore cilindrico attraversato dal fluido termovettore. Il sensore è realizzato con una molteplicità di celle solari a concentrazione calibrate, da cui il termine “collare fotovoltaico”, distribuite su un piano trasversale all’asse ottico del concentratore. Dalle misure di fotocorrente e temperatura delle celle solari si ricava l’intensità e la distribuzione della radiazione solare incidente in prossimità del tubo ricevitore.
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Papers by Alberto Mittiga
able to explain the order degree and stoichiometry effects on the Eg value is developed. Ordering results in narrower Raman peaks without affecting the shape of the photoluminescence spectrum—
except for the change in Eg—or the characteristic energy of the exponential tail below the fundamental absorption edge. Although a prolonged annealing increases the order degree, the material properties are still influenced by residual disorder as well as by defects related to the off-stoichiometry composition.
able to explain the order degree and stoichiometry effects on the Eg value is developed. Ordering results in narrower Raman peaks without affecting the shape of the photoluminescence spectrum—
except for the change in Eg—or the characteristic energy of the exponential tail below the fundamental absorption edge. Although a prolonged annealing increases the order degree, the material properties are still influenced by residual disorder as well as by defects related to the off-stoichiometry composition.