Phase and molecular orientation in metal-free phthalocyanine films on conducting glass: Characterization of two deposition methods

Alfredsson, Ylvi; Åhlund, John; Nilson, Katharina; Kjeldgaard, L.; O’Shea, James N.; Theobald, James A.; Zhaorigetu, Bao; Mårtensson, Nils; Sandell, A.; Puglia, Carla; Siegbahn, Hans

doi:10.1016/j.tsf.2005.05.012

Cited by 22 publications

(16 citation statements)

References 31 publications

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“…Typical absorbance ( A ) and LD spectra from a 0.1% film ( Fig. 1c ) show a large spectral broadening as a result of molecular interactions 22 23 24 , and exciton–vibrational coupling 17 25 26 27 . The LD spectrum is of a similar shape to the absorption and the large LD signal (about 30% of that of a commercial polarizer) observed for the bandgap spectral region, implies the majority of the transition dipoles are linearly polarized and oriented perpendicular to the pen-writing direction.…”

Section: Resultsmentioning

confidence: 99%

Polarization-resolved spectroscopy imaging of grain boundaries and optical excitations in crystalline organic thin films

et al. 2015

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Exploration of optical properties of organic crystalline semiconductors thin films is challenging due to submicron grain sizes and the presence of numerous structural defects, disorder and grain boundaries. Here we report on the results of combined linear dichroism (LD)/ polarization-resolved photoluminescence (PL) scanning microscopy experiments that simultaneously probe the excitonic radiative recombination and the molecular ordering in solution-processed metal-free phthalocyanine crystalline thin films with macroscopic grain sizes. LD/PL images reveal the relative orientation of the singlet exciton transition dipoles at the grain boundaries and the presence of a localized electronic state that acts like a barrier for exciton diffusion across the grain boundary. We also show how this energy barrier can be entirely eliminated through the optimization of deposition parameters that results in films with large grain sizes and small-angle boundaries. These studies open an avenue for exploring the influence of long-range order on exciton diffusion and carrier transport.

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Section: Resultsmentioning

confidence: 99%

Polarization-resolved spectroscopy imaging of grain boundaries and optical excitations in crystalline organic thin films

et al. 2015

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“…The observed bands do not show significant differences between flat and porous samples. For both samples, a careful deconvolution of the band envelope reveals three components: a main peak centered at 285.0 eV, due to both aliphatic and aromatic carbons [ 11 ]; a band at a binding energy (B.E.) of 286.5 eV due to the pyrrole carbons and to the shake-up related to benzene carbons, in tune with literature data [ 11 ]; and finally, a band at 288.3 eV (288.1 eV for PSi-1-Pc ) due to the shake-up transition associated with the photoionization of pyrrole [ 11 ].…”

Section: Resultsmentioning

confidence: 99%

“…The most promising architecture for the exploitation of the potentialities of Pc and M–Pc is the organization of the molecules in a suitable and accessible way on a solid surface. Therefore, phthalocyanine thin films have been deposited by using different techniques including Langmuir–Blodgett deposition [ 9 ], spin-coating [ 10 ] and vapor deposition [ 10 – 11 ]. Well-organized monolayers and multilayers have been also obtained through self-assembly [ 12 – 13 ].…”

Section: Introductionmentioning

confidence: 99%

In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

Lupo¹,

Tudisco²,

Bertani³

et al. 2014

Beilstein J. Nanotechnol.

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SummaryFree 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100) and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring–surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm−1 due to –NH stretches. Finally, XPS results revealed that the different surface–phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

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“…Functionalization of semiconductor surfaces with dye molecules is important for a number of applications, including catalysis, sensing, electronics, solar energy conversion, and many others − because of the versatile optical and electronic properties introduced by the produced interfaces. − As one of the most common and simple dye molecules, phthalocyanine (H 2 Pc) [as well as corresponding metallophthalocyanines (M-Pc)] has been widely studied and utilized for sensitization of various semiconductor surfaces, including silicon, TiO 2 , ZnO, and others . In order to achieve reproducible and robust attachment of phthalocyanine to these solid substrates, several approaches have been utilized, including spin coating, vapor deposition, and Langmuir–Blodgett deposition . However, the most stable and well-defined interfaces have been produced by making covalent bonds between phthalocyanine and solid substrates by different methods, such as chemical vapor deposition in ultra-high vacuum (UHV), ligand exchange reactions, and hydrosilylation. − Among these approaches, hydrosilylation schemes are commonly used for producing stable dye-containing organic monolayers on silicon substrates based on Si–C bonds. − Furthermore, the physical and chemical properties of the resulting dye functionality can be altered by using various M-Pc (Cu, Co, Fe, Zn, etc.)…”

Section: Introductionmentioning

confidence: 99%

29,31-H Phthalocyanine Covalently Bonded Directly to a Si(111) Surface Retains Its Metalation Ability

Teplyakov

2018

Langmuir

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The reaction of metal-free phthalocyanine molecules with a chlorine-terminated Si(111) surface is investigated to produce a phthalocyanine functionality directly attached to a semiconductor surface, without additional linkers or layers. The carefully prepared Cl-Si(111) surface provides an oxygen-free substrate that is reacted with 29,31- H phthalocyanine (HPc) in a wet-chemistry process resulting in HCl elimination. The in situ metalation of this HPc-modified silicon surface with cobalt is confirmed, suggesting that the produced functionality is chemically active. These processes are investigated by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and time-of-flight secondary ion mass spectrometry supplemented by density functional theory calculations. The morphology of the surface is monitored by atomic force microscopy. The combined spectroscopic, microscopic, and theoretical investigations demonstrate that additional linkers are not required for phthalocyanine attachment to occur, as the direct attachment can take place by forming Si-N bonds, and that the resulting surface species can participate in a metalation process.

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Phase and molecular orientation in metal-free phthalocyanine films on conducting glass: Characterization of two deposition methods

Cited by 22 publications

References 31 publications

Polarization-resolved spectroscopy imaging of grain boundaries and optical excitations in crystalline organic thin films

Polarization-resolved spectroscopy imaging of grain boundaries and optical excitations in crystalline organic thin films

In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

29,31-H Phthalocyanine Covalently Bonded Directly to a Si(111) Surface Retains Its Metalation Ability

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