Efficient Emission Facilitated by Multiple Energy Level Transitions in Uniform Graphitic Carbon Nitride Films Deposited by Thermal Vapor Condensation

Bian, Juncao; Li, Jianfu; Kalytchuk, Sergii; Wang, Yu; Li, Qian; Lau, Jenson; Niehaus, Thomas A.; Rogach, Andrey L.; Qi, Fei

doi:10.1002/cphc.201402898

Cited by 75 publications

(116 citation statements)

References 31 publications

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“…High extinction coefficients in polymeric semiconductors are mostly due to a very high density of states and high transition dipole moments and were recently also attributed to high orientation and high stiffness of the polymer chains . The extinction coefficient reveals a pronounced absorption shoulder at about 3.37 eV (λ ≈ 370 nm) attributed to π–π* transitions, in good agreement with bulk pCN (Figure S9, Supporting Information) and previous reports on pCN thin films . However, we cannot exclude at this stage also a minor contribution to the absorption due to trap states.…”

supporting

confidence: 87%

“…The excitation versus emission contour plot shows that for the peak wavelength of photoluminescence emission, i.e., 466 nm, two main excitation modes with maxima at 275 and 375 nm are present. The two excitation maxima are attributed to π–π* electronic transitions in pCN thin films, whereas, the lone pair‐π* transition appears as a shoulder at about 394 nm . However, the emission processes in pCN are complex and still under debate in the scientific community .…”

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confidence: 99%

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Shine Bright Like a Diamond: New Light on an Old Polymeric Semiconductor

et al. 2020

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Brilliance usually refers to the light reflected by the facets of a gemstone such as diamond due to its high refractive index. Nowadays, high‐refractive‐index materials find application in many optical and photonic devices and are mostly of inorganic nature. However, these materials are usually obtained by toxic or expensive production processes. Herein, the synthesis of a thin‐film organic semiconductor, namely, polymeric carbon nitride, by thermal chemical vapor deposition is presented. Among polymers, this organic material combines the highest intrinsic refractive index reported so far with high transparency in the visible spectrum, even reaching the range of diamond. Eventually, the herein presented deposition of high quality thin films and their optical characteristics open the way for numerous new applications and devices in optics, photonics, and beyond based on organic materials.

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confidence: 87%

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confidence: 99%

Shine Bright Like a Diamond: New Light on an Old Polymeric Semiconductor

et al. 2020

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“…The uniform density distribution over film cross-section is observable. It is important to note that commonly used p-CN thermal vapor condensation methods utilizing precursors materials are not effective as the film thickness control problem is not resolved [80]. The method proposed in this work utilizes p-CN as a precursor and deposition is performed at controlled thickness.…”

Section: Structural and Chemical Properties Of C 3 N Filmmentioning

confidence: 98%

Characterization of urea derived polymeric carbon nitride and resultant thermally vacuum deposited amorphous thin films: Structural, chemical and photophysical properties

Lazauskas

Baltrušaitis

Puodžiukynas

et al. 2016

Carbon

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“…In a typical PEC, the photoanode is composed of a light harvester attached to a wide band gap semiconductor (i.e., TiO 2 , ZnO) that serves as electrons acceptor layer while the holes are transferred to the counter electrode through the electrolyte solution. [18][19][20][21][22] The PEC operation is considered to be more complicated compared to the photocatalysis process due be extracted by the redox electrolyte (path 3). [4,5] Particularly, in the photoanode, excited states electrons of the light harvester must be injected into the conduction band of a wide band gap semiconductor prior their self-recombination (either radiatively or nonradiatively).…”

Section: Doi: 101002/admi201600265mentioning

confidence: 99%

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

Albero

Barea

et al. 2016

Adv Materials Inter

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to the necessity to establish a direct contact between the active materials (C 3 N 4 ) and the wide band gap semiconductor and the need of interparticle charge migration to the electrode. [23][24][25] Lately, we have succeeded to sensitize TiO 2 with C 3 N 4 by in situ deposition method that resulted in the formation of direct chemical bond between the TiO 2 and the C 3 N 4 . The intimate contact between TiO 2 and C 3 N 4 led to the absorption extension to longer wavelengths due to creation of new energy transfer paths between the materials. Moreover, the TiO 2 /C 3 N 4 system exhibited promising photocurrent densities in the presence of polysulfide as the redox electrolyte. [26] However, in comparison to the theoretical current densities the performances of this system are still low. In order to improve the cell performance, the understanding of the charge transfer reactions that limit the PEC efficiency, especially in the photoanode, is highly desired.Herein, we studied the charge recombination process between C 3 N 4 and mesoporous TiO 2 in a photoelectrode configuration using laser transient absorption spectroscopy (L-TAS). In addition, we determined the electron injection rate from the C 3 N 4 excited states to the TiO 2 conduction band by steady state and time resolved photoluminescence. Finally, the hole extraction kinetics using various liquid electrolytes and solid state hole conductors were also studied in detail. Our measurements indicate that the photoexcited electrons from C 3 N 4 can be efficiently injected to the TiO 2 conduction band, the recombination between electrons and holes from the TiO 2 conduction band and the C 3 N 4 valence band, respectively, is found to be relatively slow, thus allowing long-live charge separation. However, the hole transfer to the electrolyte was found to be the limiting process during the PEC operation. This understanding of the processes taking place within C 3 N 4 /TiO 2 photoanode can lead to the efficient C 3 N 4 -based PEC cells and photovoltaics solar cell via rational selection of hole conductor and smart electrode design.The C 3 N 4 electrodes were prepared according to our previous report. [26] Briefly, the C 3 N 4 was deposited onto mesoporous TiO 2 (which was grown on FTO glass) and nonconductive glass, respectively, by using cyanuric acid-melamine (CM) supramolecular complex as the precursor. The CM precursor was placed on top of TiO 2 electrodes or glass, totally covering the substrates and afterward the system was heated to 550 °C under nitrogen atmosphere (see also Figures S1 and S2, Supporting Information). After that the electrodes were fully characterized by a range of techniques. [26]

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Efficient Emission Facilitated by Multiple Energy Level Transitions in Uniform Graphitic Carbon Nitride Films Deposited by Thermal Vapor Condensation

Cited by 75 publications

References 31 publications

Shine Bright Like a Diamond: New Light on an Old Polymeric Semiconductor

Shine Bright Like a Diamond: New Light on an Old Polymeric Semiconductor

Characterization of urea derived polymeric carbon nitride and resultant thermally vacuum deposited amorphous thin films: Structural, chemical and photophysical properties

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

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