On the topography multiplicity of non-planar titanyl (IV) phthalocyanine molecules and the STM imaging mechanism

Kong, Xianghua; Yang, Yan; Lei, Shengbin; Wang, Chen

doi:10.1016/j.susc.2007.11.027

Cited by 17 publications

(34 citation statements)

References 39 publications

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“…[255] UPS was used to characterize the frontier energy levels, LUMO energies were estimated from combinations of optical gaps, IPES experiments on comparable donors and acceptors, and STS experiments. [206,207,219] The energy offsets E LUMO D À E LUMO A for pentacene/C 60 thin films predict the highest J SC among the three possible heterojunctions, which is confirmed by the data in Figure 6B, and by several other previous studies. [26,54,55,196,236,256] TiOPc is not typically used as an electron acceptor and electron transport material, and the reasons for lower photocurrent production may result from trapping of charges and low charge mobilities.…”

Section: For Many O/osupporting

confidence: 87%

Organic/Organic′ Heterojunctions: Organic Light Emitting Diodes and Organic Photovoltaic Devices

Armstrong

Wang

Alloway

et al. 2009

Macromol. Rapid Commun.

190

122

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Heterojunctions created from thin films of two dissimilar organic semiconductor materials [organic/organic' (O/O') heterojunctions] are an essential component of organic light emitting diode displays and lighting systems (OLEDs, PLEDs) and small molecule or polymer-based organic photovoltaic (solar cell) technologies (OPVs). O/O' heterojunctions are the site for exciton formation in OLEDs, and the site for exciton dissociation and photocurrent production in OPVs. Frontier orbital energy offsets in O/O' heterojunctions establish the excess free energy controlling rates of charge recombination and formation of emissive states in OLEDs and PLEDs. These energy offsets also establish the excess free energy which controls charge separation and the short-circuit photocurrent (J(SC) ) in OPVs, and set the upper limit for the open-circuit photopotential (V(OC) ). We review here how these frontier orbital energy offsets are determined using photoemission spectroscopies, how these energies change as a function of molecular environment, and the influence of interface dipoles on these frontier orbital energies. Recent examples of heterojunctions based on small molecule materials are shown, emphasizing those heterojunctions which are of interest for photovoltaic applications. These include heterojunctions of perylenebisimide dyes with trivalent metal phthalocyanines, and heterojunctions of titanyl phthalocyanine with C(60) , and with pentacene. Organic solar cells comprised of donor/acceptor pairs of each of these last three materials confirm that the V(OC) scales with the energy offsets between the HOMO of the donor and LUMO of the acceptor ($E_{{\rm HOMO}^{\rm D} } - E_{{\rm LUMO}^{\rm A} }$).

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Section: For Many O/osupporting

confidence: 87%

Organic/Organic′ Heterojunctions: Organic Light Emitting Diodes and Organic Photovoltaic Devices

Armstrong

Wang

Alloway

et al. 2009

Macromol. Rapid Commun.

190

122

View full text Add to dashboard Cite

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“…Tilted adsorption was also observed for the free-base 2HOEP monolayer on Ag (1 1 1) Section 6) resulted in a slight increase of the measured tilt angle to 211. Similar measurements before and after metalation with Fe were also performed for a 2HOEP multilayer, resulting in tilt angles of 221-421 and 271 for 2HOEP and FeOEP, respectively.…”

Section: Tetrapyridylporphyrinssupporting

confidence: 60%

“…At low coverages, close-packed domains consisting of zigzag chains of (O) TiPc molecules were observed [206]. (O)TiPc has also been studied at the electrochemical interface on HOPG [210] and Au (1 1 1) [211]. (O)VPc adsorbed on HOPG (in vacuum) in an oxygen-up orientation [212,213], while mixed orientations were observed on Cu(1 1 1) and Au(1 1 1) [213].…”

Section: Adsorption Of Simple Metallophthalocyanines On Metalsmentioning

confidence: 99%

Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

583

586

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“…We crystals and liquid/solid interface 11,12,26 and are significantly smaller than those previously reported for STM data in UHV. [27][28][29]32 We investigated the photo-responses of molecules in the TiOPc hexagonal lattice using laser-assisted STM with 633 nm (3.5 mW) laser illumination.…”

Section: Resultscontrasting

confidence: 62%

“…[13][14][15][16][17][18][19][20][21][22][23][24][25] Scanning tunneling microscopy (STM) has been used to study the adsorption of TiOPc molecules on various surfaces. 10, [26][27][28][29][30][31][32] In most of these studies, the deposition of TiOPc molecules was conducted in ultra-high vacuum (UHV) and therefore the arrangements of the molecules are significantly different from TiOPc crystals. When approaching low surface coverages (i.e., < 1 monolayer), TiOPc molecules adsorb on metal surfaces with their phthalocyanine plane parallel to the substrates.…”

mentioning

confidence: 99%

Photoinduced Carrier Generation and Distribution in Solution-Deposited Titanyl Phthalocyanine Monolayers

et al. 2019

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We prepared titanyl phthalocyanine (TiOPc) monolayers on sapphire-prism supported Au{111} substrates through solution deposition and characterized their photo-responses using a custom-built laser-assisted scanning tunneling microscope under ambient conditions. Two types of lattice structures (hexagonal and rectangular) were observed and the distributions of photo-induced charges were measured under evanescently introduced 633 nm and 780 nm laser illumination. The distributions of photoelectrons in molecules in hexagonal lattices match theoretically calculated charge density changes in TiOPc molecules upon excitation. However, the photo-responses of TiOPc molecules in rectangular lattices are different than those predicted and TiOPc molecules in these arrangements may have lower excitation probabilities at 633 nm and 780 nm. Our results suggest that the photo carrier generation efficiency of TiOPc molecules is related to their packing arrangements in monolayers and local environments.

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On the topography multiplicity of non-planar titanyl (IV) phthalocyanine molecules and the STM imaging mechanism

Cited by 17 publications

References 39 publications

Organic/Organic′ Heterojunctions: Organic Light Emitting Diodes and Organic Photovoltaic Devices

Organic/Organic′ Heterojunctions: Organic Light Emitting Diodes and Organic Photovoltaic Devices

Surface chemistry of porphyrins and phthalocyanines

Photoinduced Carrier Generation and Distribution in Solution-Deposited Titanyl Phthalocyanine Monolayers

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