Electrochemical enhancement of optoelectronic performance of transparent and conducting single-walled carbon nanotube films

Kopylova, Daria S.; Satco, Daria A.; Khabushev, Eldar M.; Bubis, Anton V.; Krasnikov, Dmitry V.; Kallio, Tanja; Nasibulin, Albert G.

doi:10.1016/j.carbon.2020.05.103

Cited by 22 publications

(13 citation statements)

References 39 publications

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“…The spectral sensitivity of the PV response upon ionic gating changes in the external quantum efficiency (EQE) of small-molecule OPV is less extended, as compared to the EQE modulation in polymeric BHJ OPV, as shown in the Supporting Information in Figure S5. Indeed, in BHJ OPV with PTB7–PCBM-type BHJ, the EQE increases from 40% to over 50% (at 200 nm peak), and the main effect on EQE comes from the change of optical absorption of MWCNTs at the IR tail (upon doping), and C 60 and PCBM in the UV range increasing the 200 nm tails upon IL n-doping, while ionic salt molecules themselves do not contribute to optical absorption and MWCNTs, are still less sensitive to doping effects as compared to SWCNTs (which in fact become more transparent upon ionic gating doping , ).…”

Section: Resultsmentioning

confidence: 99%

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Saranin

Mahmoodpoor

Voroshilov

et al. 2021

ACS Appl. Mater. Interfaces

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We demonstrate an improvement in the performance of organic photovoltaic (OPV) systems based on small molecules by ionic gating via controlled reversible n-doping of multi-wall carbon nanotubes (MWCNTs) coated on fullerene electron transport layers (ETLs): C60 and C70. Such electric double-layer charging (EDLC) doping, achieved by ionic liquid (IL) charging, allows tuning of the electronic concentration in MWCNTs and the fullerene planar acceptor layers, increasing it by orders of magnitude. This leads to the decrease of the series and increase of the shunt resistances of OPVs and allows use of thick (up to 200 nm) ETLs, increasing the durability of OPVs. Two stages of OPV enhancement are described upon the increase of gating bias V g: at small (or even zero) V g, the extended interface of ILs and porous transparent MWCNTs is charged by gating, and the fullerene charge collector is significantly improved, becoming an ohmic contact. This changes the S-shaped J–V curve via improving the electron collection by an n-doped MWCNT cathode with an ohmic interfacial contact. The J–V curves further improve at higher gating bias V g due to the increase of the Fermi level and decrease of the MWCNT work function. At the next qualitative stage, the acceptor fullerene layer becomes n-doped by electron injection from MWCNTs while ions of ILs penetrate into the fullerene. At this step, the internal built-in field is created within OPV, which helps in exciton dissociation and charge separation/transport, increasing further the J sc and the fill factor. The ionic gating concept demonstrated here for most simple classical planar small-molecule OPV cells can be potentially applied to more complex highly efficient hybrid devices, such as perovskite photovoltaic with an ETL or a hole transport layer, providing a new way to tune their properties via controllable and reversible interfacial doping of charge collectors and transport layers.

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Section: Resultsmentioning

confidence: 99%

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Saranin

Mahmoodpoor

Voroshilov

et al. 2021

ACS Appl. Mater. Interfaces

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“…Suppression of the optical absorption bands of nanotubes is a consequence of the Burstein–Moss shift, , usually observed in degenerate semiconductors. For the SWCNTs, this significantly affects the optical properties of the samples. ,, As in the case of Raman scattering, both methods for varying the impurity concentration (step-by-step doping or different times of exposure to copper chloride) lead to a gradual shift in the Fermi level position, which is manifested in the gradual suppression of the absorption spectra (Figure a). Similar effects are observed when dopants with different concentrations are deposited on the surface of CNTs .…”

Section: Resultsmentioning

confidence: 99%

“…However, it is often important to improve and to tune multiple characteristics of a functional material within the framework of a single technique. For macro-objects based on carbon nanomaterials, tuning is required for the position of the Fermi level, the work function (WF) of the material, and therefore, the optical density and transport characteristics. − Control of these properties is necessary for various electronic and optoelectronic devices, such as organic field-effect transistors (OFETs), organic photovoltaic systems, sensors, and heterostructures. , The technological methods for tuning the characteristics of micro- and macro-objects in most cases are based on the deposition of active substances on the surface of nanotubes or other nanomaterials. ,, However, these approaches lead to material contamination, making them difficult to use.…”

Section: Introductionmentioning

confidence: 99%

Tunable Doping and Characterization of Single-Wall Carbon Nanotube Macrosystems for Electrode Material Applications

Tonkikh

Eremina

Obraztsova

et al. 2021

ACS Appl. Nano Mater.

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We present an efficient method for easy tuning of optical and electrophysical parameters of macroscopic objects formed from single-wall carbon nanotubes (SWCNTs). We have developed a unique step-by-step doping procedure by filling the SWCNT inner channels with acceptors and donors in gaseous conditions. The main parameter that tailors the film properties is the dopant concentration in the SWCNT channels varied through the gaseous filling time. The ambient oxygen impact on the doping level has been measured and analyzed for all considered SWCNT objects. Our approach provides a predictable shift of Fermi level position in the range of 0.1−0.9 eV and the optical band gap edge value between 0.4 and 1.1 eV. The tuning method was applied to optimize the thermopower performance of SWCNT films. We have measured the maximum possible values of the power factor and thermoelectric coefficient and studied the stability of these parameters in the air for studied samples. On the basis of the revealed relation between thermopower and sheet resistance, we propose a general approach for characterization of conducting CNT macro-objects, which we call the "doping map" plotting. This empirical method allows to predict stable, maximum, or optimal values for the transport, thermopower, and optical characteristics of materials in the air. Our findings are prospective for prediction and tailoring of SWNT-containing materials properties used in such technological applications, as electrochemical, sensor, solar cell, or thermoelectric electrode materials.

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“…Single‐wall carbon nanotubes (SWCNTs) are a promising material for use in photonic and optoelectronic applications [ 1–2 ] due to their superior properties of high carrier mobility, [ 3 ] structure‐tunable bandgap, [ 4 ] and broad optical response. [ 5 ] In particular, the optoelectronic properties of SWCNTs can be modulated by sidewall noncovalent functions, [ 6–10 ] covalent functions, [ 11–14 ] or external electric fields, [ 3,15–22 ] which can broaden the potential application of SWCNTs for biosensors, [ 23,24 ] light emitters and detectors. [ 25,26 ] For example, by creating sp 3 covalent defect dopant states with different emission energies and achieving potential traps deeper than the thermal energy, SWCNT‐based single‐photon sources with desired properties can be produced.…”

Section: Introductionmentioning

confidence: 99%

“…[ 25,26 ] For example, by creating sp 3 covalent defect dopant states with different emission energies and achieving potential traps deeper than the thermal energy, SWCNT‐based single‐photon sources with desired properties can be produced. [ 12 ] By selectively tuning the Fermi level in SWCNTs into the valence (or conduction) band by chemical or electrical gate doping, the optical transitions between the two different subbands and thus the optical properties of SWCNTs can be finely controlled, [ 15–17,19,20,27,28 ] which provides a platform for designing next‐generation nanoelectronic devices. Among them, electrical gate doping with ionic liquids has advantages in regard to the modulation depth, operating speed of the Fermi level and compatibility with semiconductor processing methods, [ 17,19,21 ] which makes SWCNTs highly attractive for applications in electro‐optical modulators, [ 17,29,30 ] photovoltaic devices, [ 31 ] optical communications, [ 2,32,33 ] and so on.…”

Section: Introductionmentioning

confidence: 99%

Electronic Type and Diameter Dependence of the Intersubband Plasmons of Single‐Wall Carbon Nanotubes

Wang

Yang

et al. 2021

Adv Funct Materials

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The intersubband plasmons (ISBPs) of single‐wall carbon nanotubes (SWCNTs) endow SWCNT‐based optoelectronic devices with more functions. However, the structural dependence of the ISBPs of SWCNTs is not fully understood. Here, the effect of electronic types and diameters of SWCNTs on the energy and intensity of their ISBPs is investigated systematically. The results show that the ISBP energy of semiconducting SWCNTs is ≈50–250 meV larger than that of metallic SWCNTs with the same diameters, while the ISBP integral intensity is approximately 1.25 to 4 times stronger. Diameter dependence of ISBPs for both semiconducting and metallic SWCNTs is also observed. With a decrease in diameter, the ISBPs shift to higher energies, while the intensity decreases dramatically. When the diameter is reduced to less than 1 nm, the ISBPs become unobservable. Interestingly, the energy separation between the ISBPs and interband transition S22 (M11) decreases with an increase in diameter. Theoretical calculations show that the structure‐dependent ISBP characteristics are dominated by the electronic states of SWCNTs. Based on the ISBP characteristics of different SWCNTs, high‐performance SWCNT‐based near‐infrared electrochromic devices are fabricated by mixing small‐diameter metallic SWCNTs with semiconducting SWCNTs due to their high conductivity and negligible ISBP signals.

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Electrochemical enhancement of optoelectronic performance of transparent and conducting single-walled carbon nanotube films

Cited by 22 publications

References 39 publications

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer

Tunable Doping and Characterization of Single-Wall Carbon Nanotube Macrosystems for Electrode Material Applications

Electronic Type and Diameter Dependence of the Intersubband Plasmons of Single‐Wall Carbon Nanotubes

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