Juan Cabanillas-Gonzalez

Publications (6)35.58 Total impact

• Source

  Available from: imdea.org

  Article: Pump-probe spectroscopy in organic semiconductors: monitoring fundamental processes of relevance in optoelectronics.

  Juan Cabanillas-Gonzalez, Giulia Grancini, Guglielmo Lanzani
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  ABSTRACT: In this review we highlight the contribution of pump-probe spectroscopy to understand elementary processes taking place in organic based optoelectronic devices. The techniques described in this article span from conventional pump-probe spectroscopy to electromodulated pump-probe and the state-of-the-art confocal pump-probe microscopy. The article is structured according to three fundamental processes (optical gain, charge photogeneration and charge transport) and the contribution of these techniques on them. The combination of these tools opens up new perspectives for assessing the role of short-lived excited states on processes lying underneath organic device operation.
  Advanced Materials 12/2011; 23(46):5468-85. · 13.88 Impact Factor
• Article: Transient Absorption Imaging of P3HT:PCBM Photovoltaic Blend: Evidence For Interfacial Charge Transfer State

  Giulia Grancini, Dario Polli, Daniele Fazzi, Juan Cabanillas-Gonzalez, Giulio Cerullo, Guglielmo Lanzani
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  ABSTRACT: Solution-processed bulk heterojunction (BHJ) based on electron-donor (D) polymer and acceptor (A) fullerene is a promising technology for organic photovoltaics. Geminate charge recombination is regarded as one of the main loss mechanisms limiting device performances. This stems from the dynamics of the initial charge transfer state (CTS), which depend on the blend morphology, the molecular conformation, and the energetics of the D:A interface. Here we study the photophysics of a crystalline phase-separated blend of regioregular poly(3-hexylthiophene) (P3HT) with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) with a coarsened morphology, by mapping the transient absorption signal with submicrometer space and subpicosecond time resolution. At the P3HT:PCBM interface, we detect a long-lived photoinduced dynamic that we assign to a peculiar coherent CTS forming in 10 ps, not affected by geminate recombination and characterized by a different polarization with respect to the one in the usual polydispersed blend. Quantum chemical calculations on supramolecular P3HT:PCBM complexes confirm the presence of low-lying and highly polarized CTS, validating the experimental findings.Keywords: pump probe spectroscopy; confocal imaging; bulk heterojunction; charge transfer state; quantum chemical calculations
  04/2011;
• Article: Imaging the Electric‐Field Distribution in Organic Devices by Confocal Electroreflectance Microscopy

  Michele Celebrano, Calogero Sciascia, Giulio Cerullo, Margherita Zavelani-Rossi, Guglielmo Lanzani, Juan Cabanillas-Gonzalez
  Advanced Functional Materials 02/2009; 19(8):1180 - 1185. · 10.18 Impact Factor
• Article: Combined spectroscopic characterization of electron transfer at hybrid CuPcF(16)/GaAs semiconductor interfaces.

  Juan Cabanillas-Gonzalez, Hans-Joachim Egelhaaf, Alberto Brambilla, Paolo Sessi, Lamberto Duò, Marco Finazzi, Franco Ciccacci, Guglielmo Lanzani
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  ABSTRACT: We characterize photoinduced charge injection at the interface between a fluorinated copper phthalocyanine (CuPcF(16)) film deposited over a GaAs(100) wafer by means of pump-probe spectroscopy combined with ultraviolet photoemission spectroscopy (UPS) and electromodulated transmission spectroscopy. UPS characterization of the hybrid interface demonstrates that the CuPcF(16) 's lowest unoccupied molecular level (LUMO) is almost aligned with the GaAs conduction band. Upon photoexcitation of the hybrid interface with 150 fs pulses we observe an efficient photoinduced electron transfer from CuPcF(16) to GaAs. The evolution of interfacial CuPcF(16) charges appear to be strongly influenced by energy level alignment at the GaAs/CuPcF(16) heterojunction.
  Nanotechnology 10/2008; 19(42):424010. · 3.98 Impact Factor
• Source

  Available from: Stefano Toffanin

  Article: Molecular packing effects on the optical spectra and triplet dynamics in oligofluorene films.

  Juan Cabanillas-Gonzalez, Calogero Sciascia, Guglielmo Lanzani, Stefano Toffanin, Raffaella Capelli, Miguel C Ramon, Michele Muccini, Johannes Gierschner, Tsyr-Yuan Hwu, Ken-Tsung Wong
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  ABSTRACT: We report on the triplet spectra and dynamics in two types of oligomeric films deposited by two different techniques: thermal evaporation and spin coating. The different molecular arrangement in both films is manifested in a red shift of the absorption, PL, and T1-Tn absorption spectra of the sublimated film relative to the spin-coated one. Triplet recombination dynamics studied with steady-state photoinduced absorption (PA) spectroscopy follow a dispersive bimolecular recombination model away from the trap filling regime. We obtained values for the triplet bimolecular recombination ratio (beta) of 3.4 x 10 (-14) and 1.1 x 10 (-15) cm3 s (-1) for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films.
  The Journal of Physical Chemistry B 09/2008; 112(37):11605-9. · 3.70 Impact Factor
• Article: Kinetics of interfacial charges in hybrid GaAs/oligothiophene semiconducting heterojunctions

  Juan Cabanillas-Gonzalez, Alessio Gambetta, Margherita Zavelani-Rossi, Guglielmo Lanzani
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  ABSTRACT: The authors report on pump-probe measurements in a hybrid heterostructure consisting of a modified oligothiophene layer deposited over a GaAs substrate. Upon photoexcitation of the bilayer with 100 fs, a new photoinduced absorption band (PA2) appeared being attributed to oligothiophene cations arising from exciton diffusion and dissociation at the hybrid inorganic/organic interface. An exciton diffusion length in the organic layer of approximately 3.4 nm was estimated.
  Applied Physics Letters 09/2007; 91(12):122113-122113-3. · 3.84 Impact Factor