Controlling Surface Potential of Graphene Using dc Electric Field

Due to the attraction of fabricating highly efficient tandem solar cells, wide‐bandgap perovskite solar cells (PSCs) have attracted substantial interest in recent years. However, polycrystalline perovskite thin‐films show the existence of trap states at grain boundaries which diminish the optoelectronic properties of the perovskite and thus remains a challenge. Here, a one‐step solution‐processing of [ MA0.9Cs0.1Pbfalse(I0.6Br0.4false)3] wide‐bandgap perovskite using phenylhydrazine iodide with amino groups is demonstrated to successfully passivate the trap density within grain boundaries and increase the perovskite grain size. The reinforced morphology and grain boundaries treatment considerably enhanced the power conversion efficiency (PCE) from 12.16% for pristine to 14.63% for the treated devices. This strategy can be easily adopted to other perovskites and help realize highly efficient perovskite solar cells.

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“…KPFM measurement was performed to investigate

V_{CPD}

which tells the work function difference between the AFM tip and the perovskite local surface.

V_{CPD}

was measured between the conductive tip of the KPFM and the perovskite film and calculated by the following equation [ 38–40 ]

V_{CPD} = \frac{{normalΦ}_{tip} - {normalΦ}_{normals}}{- e}

…”

Section: Resultsmentioning

confidence: 99%

Tailoring the Grain Boundaries of Wide‐Bandgap Perovskite Solar Cells by Molecular Engineering

et al. 2020

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“…These results suggest that the lower surface potential with an electronic stable status of the GQD-doped ZnO layer exhibit a higher work function than the pristine ZnO layer. 48 Accordingly, an energy level mismatch occurred, resulting in a slightly low V OC of 0.858 V because the introduction of the GQD-doped ZnO layer rather than the pristine ZnO layer formed relatively large energy barriers. In other words, the enhanced emission intensity occurred mainly owing to energy transfer by introducing the GQD-doped ZnO layer.…”

Section: Table 1 Photovoltaic Performances Of Fabricated Oscs Under 1...mentioning

confidence: 99%

High-Performance Nonfullerene Organic Photovoltaics Applicable for Both Outdoor and Indoor Environments through Directional Photon Energy Transfer

Han

Jung

Lee

et al. 2020

ACS Appl. Mater. Interfaces

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With the advent of the smart factory and the Internet of Things (IoT) sensors, organic photovoltaics (OPVs) gained attention because of their ability to provide indoor power generation as an off-grid power supply. To satisfy these applications, OPVs must be capable of power generation in both outdoor and indoor at the same time for developing environmentally independent devices. For high performances in indoor irradiation, a strategy that maximizes photon utilization is essential. In this study, graphene quantum dots (GQDs), which have unique emitting properties, are introduced into a ZnO layer for efficient photon utilization of nonfullerene-based OPVs under indoor irradiation. GQDs exhibit high absorption properties in the 350–550 nm region and strong emission properties in the visible region due to down-conversion from lattice vibration. Using these properties, GQDs provide directional photon energy transfer to the bulk-heterojunction (BHJ) layer because the optical properties overlap. Additionally, the GQD-doped ZnO layer enhances shunt resistance (R Sh) and forms good interfacial contact with the BHJ layer that results in increased carrier dissociation and transportation. Consequently, the fabricated device based on P(Cl-Cl)(BDD = 0.2) and IT-4F introduces GQDs exhibiting a maximum power conversion efficiency (PCE) of 14.0% with a superior enhanced short circuit current density (J SC) and fill factor (FF). Furthermore, the fabricated device exhibited high PCEs of 19.6 and 17.2% under 1000 and 200 lux indoor irradiation of light emitting diode (LED) lamps, respectively.

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“…Electrostatic force microscopy is a useful technique for investigating the electrical properties of nanomaterials and has been extensively used to study the distribution of electrical potential and charge at the nanoscale for graphene and graphene oxide [92]- [95]. Qualitative mapping of the surface potential is primarily undertaken with EFM.…”

Section: Electrical Properties Efm and 4-point Probe Sheet Resistancementioning

confidence: 99%

Efficient hole transport material formed by atmospheric pressure plasma functionalization of Spiro-OMeTAD

Ghosh

Ivaturi

Bhattacharya

et al. 2020

Materials Today Chemistry

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A technique to increase the conductivity of Spiro-OMeTAD using an easily scalable, nonthermal atmospheric pressure plasma jet (APPJ) is reported. An investigation of plasma functionalization demonstrated an enhancement in hole conductivity by over an order of magnitude from 9.4 × 10-7 S cm-1 for the pristine film to 1.15 × 10-5 S cm-1 for films after 5 minutes of plasma treatment. The conductivity value after plasma functionalization was comparable to that reported for 10 -25% Li-TFSI-doped Spiro-OMeTAD. The increase in conductivity was correlated with a reduction in phase value observed using electrostatic force microscopy. Kelvin probe force microscopy showed an increase in work function after plasma exposure corresponding to the p-type nature of the doping. X-ray photoelectron spectroscopy revealed surface oxidation of plasma-functionalized films, as well as variation in nitrogen chemistry, with the formation of a higher binding energy quaternary nitrogen tail. Oxidation of Spiro-OMeTAD was also confirmed by the appearance of the 500 nm absorption peak using UV-vis spectroscopy. The synergistic contribution of increase in charge density in Spiro-OMeTAD due to the energetic species in the plasma jet coupled with improvement in π-π stacking of the molecules is thought to underlie the conductivity enhancement. We also attribute the formation of quinoid structures with quaternary nitrogen +N=C to the enhancement in positive charge centres due to loss of methoxy groups during plasma-surface interaction. This work opens up the possibility of using an atmospheric pressure plasma jet as a simple and effective technique for doping and functionalizing Spiro-OMeTAD thin films to circumvent the detrimental issues associated with chemical dopants.

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Controlling Surface Potential of Graphene Using dc Electric Field

Cited by 4 publications

References 16 publications

Tailoring the Grain Boundaries of Wide‐Bandgap Perovskite Solar Cells by Molecular Engineering

Tailoring the Grain Boundaries of Wide‐Bandgap Perovskite Solar Cells by Molecular Engineering

High-Performance Nonfullerene Organic Photovoltaics Applicable for Both Outdoor and Indoor Environments through Directional Photon Energy Transfer

Efficient hole transport material formed by atmospheric pressure plasma functionalization of Spiro-OMeTAD

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