Conventional solar cells exhibit limited efficiencies in part due to their inability to absorb the entire solar spectrum. Sub-band-gap photons are typically lost but could be captured if a material that performs up-conversion, which shifts photon energies higher, is coupled to the device. Recently, molecular chromophores that undergo triplet-triplet annihilation (TTA) have shown promise for efficient up-conversion at low irradiance, suitable for some types of solar cells. However, the molecular systems that have shown the highest up-conversion efficiency to date are ill suited to broadband light harvesting, reducing their applicability. Here we overcome this limitation by combining an organic TTA system with highly fluorescent CdSe semiconductor nanocrystals. Because of their broadband absorption and spectrally narrow, size-tunable fluorescence, the nanocrystals absorb the radiation lost by the TTA chromophores, returning this energy to the up-converter. The resulting nanocrystal-boosted system shows a doubled light-harvesting ability, which allows a green-to-blue conversion efficiency of μ12.5% under 0.5 suns of incoherent excitation. This record efficiency at subsolar irradiance demonstrates that boosting the TTA by light-emitting nanocrystals can potentially provide a general route for up-conversion for different photovoltaic and photocatalytic applications.

Monguzzi, A., Braga, D., Gandini, M., Holmberg, V., Kim, D., Sahu, A., et al. (2014). Broadband up-conversion at subsolar irradiance: Triplet-triplet annihilation boosted by fluorescent semiconductor nanocrystals. NANO LETTERS, 14(11), 6644-6650 [10.1021/nl503322a].

Broadband up-conversion at subsolar irradiance: Triplet-triplet annihilation boosted by fluorescent semiconductor nanocrystals

MONGUZZI, ANGELO MARIA
Primo
;
BRAGA, DANIELE
Secondo
;
GANDINI, MATTEO;MEINARDI, FRANCESCO
2014

Abstract

Conventional solar cells exhibit limited efficiencies in part due to their inability to absorb the entire solar spectrum. Sub-band-gap photons are typically lost but could be captured if a material that performs up-conversion, which shifts photon energies higher, is coupled to the device. Recently, molecular chromophores that undergo triplet-triplet annihilation (TTA) have shown promise for efficient up-conversion at low irradiance, suitable for some types of solar cells. However, the molecular systems that have shown the highest up-conversion efficiency to date are ill suited to broadband light harvesting, reducing their applicability. Here we overcome this limitation by combining an organic TTA system with highly fluorescent CdSe semiconductor nanocrystals. Because of their broadband absorption and spectrally narrow, size-tunable fluorescence, the nanocrystals absorb the radiation lost by the TTA chromophores, returning this energy to the up-converter. The resulting nanocrystal-boosted system shows a doubled light-harvesting ability, which allows a green-to-blue conversion efficiency of μ12.5% under 0.5 suns of incoherent excitation. This record efficiency at subsolar irradiance demonstrates that boosting the TTA by light-emitting nanocrystals can potentially provide a general route for up-conversion for different photovoltaic and photocatalytic applications.
Articolo in rivista - Articolo scientifico
colloidal quantum dots; photocatalysis; photovoltaics; semiconductor nanocrystals; triplet-triplet annihilation; Up-conversion; Condensed Matter Physics; Bioengineering; Chemistry (all); Materials Science (all); Mechanical Engineering
English
2014
14
11
6644
6650
none
Monguzzi, A., Braga, D., Gandini, M., Holmberg, V., Kim, D., Sahu, A., et al. (2014). Broadband up-conversion at subsolar irradiance: Triplet-triplet annihilation boosted by fluorescent semiconductor nanocrystals. NANO LETTERS, 14(11), 6644-6650 [10.1021/nl503322a].
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/83934
Citazioni
  • Scopus 60
  • ???jsp.display-item.citation.isi??? 59
Social impact