The Kelvin probe, used to measure changes in work function (wf), has proved particularly useful as a UHV surface analysis technique, having applications the study of thin films, adsorption kinetics, photovoltage spectroscopy, topographies, etc. However circuit is plagued by noise problems, which are considerably enhanced long connecting wires and nonideal environment. Careful shielding essential order improve signal-to-noise (S/N) ratio, especially at backing potentials close null condition....

The field of organo-lead halide perovskite solar cells has been rapidly growing since their discovery in 2009. State the art devices are now achieving efficiencies comparable to much older technologies like silicon, while utilising simple manufacturing processes and starting materials. A key parameter consider when optimising cell or designing new materials is position effects energy levels We present here a comprehensive study common structure using an advanced macroscopic Kelvin probe UV...

Increasing the open-circuit voltage (Voc) is one of key strategies for further improvement efficiency perovskite solar cells. It requires fundamental understanding complex optoelectronic processes related to charge carrier generation, transport, extraction, and their loss mechanisms inside a device upon illumination. Herein, we report important origin Voc losses in methylammonium lead iodide (MAPI)-based cells, which results from undesirable positive (hole) accumulation at interface between...

We have developed a novel, low cost, scanning Kelvin probe (SKP) system that can measure work function (wf) and surface potential (sp) topographies to within 1 meV energy resolution. The control measurement subcomponents are PC based incorporate flexible user interface, permitting software of major parameters allowing easy implementation via automatic setup procedures. review the mode operation design features SKP including digital oscillator, compact ambient voice-coil head-stage, signal...

We describe a novel photoemission technique utilizing traditional Kelvin probe as detector of electrons/atmospheric ions ejected from metallic surfaces (Au, Ag, Cu, Fe, Ni, Ti, Zn, Al) illuminated by deep ultra-violet (DUV) source under ambient pressure. To surmount the limitation electron scattering in air incident photon energy is rastered rather than applying variable retarding electric field used with UPS. This arrangement can be applied several operational modes: using DUV to determine...

We have developed a novel multitip scanning Kelvin probe which can measure changes in biological surface potential ΔVs to within 2 mV and, quasisimultaneously monitor displacement <1 μm. The control and measurement subcomponents are PC based incorporate flexible user interface permitting software of each individual tip, measurement, scan parameters. review the mode operation design features bio-Kelvin including tip steering, signal processing, calibration, tracking/dithering routines....

We present a theoretical analysis of the Kelvin probe circuit taking into account both parallel capacity induced by connecting cables and fringing fields. demonstrate simple explicit solution for low modulation index ε suggest an optimized detection method close to unity. extend include stray capacitance terms static- vibrating-plate earthed (spe, vpe) configurations examine variation in apparent contact potential difference Vapp as function mean spacing. This is primarily intended UHV...

Alloyed triple A-cation perovskites containing a mixture of Cs, methylammonium (MA), and formamidinium (FA) cations are attracting intense attention because their high photovoltaic performance relative stability. However, there is limited fundamental understanding vacancy defect behaviour influence molecular oxygen on electronic stability properties. In this combined computational–experimental study, we investigate the (FA,MA,Cs)Pb(I,Br)3 model system with its simulated atomistic structure...

This article describes a new type of in situ ultrahigh-vacuum compatible kelvin probe based on voice-coil driving mechanism. design exhibits several advantages over conventional mechanical feed-through and (in situ) piezoelectric devices regard to the possibility multiple geometry, flexibility amplitude oscillation, pure parallel vibration. Automatic setup constant spacing features are achieved using digital-to-analog converter (DAC) steered offset potential. The combination very low driver...

Semiconductor devices require conducting electrodes with disparate work functions for their operation. Of recent interest are fluidic processing approaches large-area devices, which present unique challenges in the identification of materials having but similar melting temperatures. Such may be engineered by alloying low-melting temperature metals. As a demonstration, function tin and four binary alloys is measured ultraviolet photoemission spectroscopy Kelvin probe method. We demonstrate...

Although ambient processing is the key to low-cost organic solar cell production, high-vacuum thermal evaporation of LiF often a limiting step, motivating exploration solution as an alternative electrode interlayer. Submonolayer films are realized with assistance polymeric micelle reactors that enable particle deposition controlled nanoscale surface coverage. Scanning Kelvin probe reveals work function tunable nanoparticle coverage higher values than bare indium tin oxide (ITO).

The charge density of a film deposited on -passivated silicon wafer is determined. by atmospheric pressure chemical vapor deposition at , and the grown thermally . This stack useful coating for front surface solar cell, as it has high optical transmission low interface states interface. While these properties are beneficial to efficiency cells, so too large density, what occurs in stacks. -coated evaluated capacitance–voltage Kelvin probe measurements. within conservative limits −8.5 after...

Triboemission – i.e. the emission of photons, electrons and other charged particles that arise from a sliding contact may play key role in tribochemical processes, such as lubricant degradation. However, mechanisms give rise to this type are not well understood. For first time, we present spatially resolved measurements electron emission, obtained range materials worn. These scratch tests, carried out under vacuum conditions (10−5 Torr), which microchannel plates coupled phosphor screen used...

We describe a novel dual-mode Kelvin probe featuring ambient pressure Photoemission Spectroscopy (PES), which yields information on the absolute work function (Φ) of metal and Ionisation Potential (IP) semiconductor, coupled with high resolution Contact Difference capability can be extended to Surface Photovoltage measurements. The relative energy are 50 meV for PES 1-3 CPD. To surmount limitation electron scattering in air incident photon is rastered rather than applying variable retarding...

Abstract We describe a novel photoemission technique utilizing traditional Kelvin probe as detector of electrons/atmospheric ions ejected from metal and semiconductor surfaces (Al, Ag, Au, Si) illuminated by Deep Ultra‐Violet (DUV) source at ambient pressure. In Constant Final State Yield Spectroscopy (CFSYS) the incident photon energy is rastered rather than applying variable retarding electric field in conventional UPS. For both ambient‐ near pressure‐photoemission spectroscopy (NAP‐PES)...

We have performed a study of high- (>6 eV) and low- (<3 work-function surfaces in order to identify suitable target materials as an ion source for new type mass spectrometer technique based on hyperthermal surface ionization (HSI). In this application molecular beam neutral gas molecules is ionized by supersonic collision surface. High-work-function produce positive ions (pHSI), low-work-function negative (nHSI). Analytical merits HSI include very high sensitivity, atmospheric...

Objective. Acupuncture points are reportedly distinguishable by their electrical properties. However, confounders arising from skin-to-electrode contact used in traditional electrodermal methods have contributed to controversies over this claim. The Scanning Kelvin Probe is a state-of-the-art device that measures potential without actually touching the skin and thus capable of overcoming these confounding effects. In study, we evaluated profiles acupoints LI-4 PC-6 adjacent controls. We...

We have undertaken a study of high work function (φ) surfaces as part an ongoing project searching for efficient target materials use in hyperthermal surface ionization (HSI), new mass spectroscopy technique. HSI relies on φ the production positive ions. Rhenium is particularly interesting this respect oxidation substantially increases to approximately 7 eV. Using novel ultrahigh vacuum scanning Kelvin probe and Auger electron we followed kinetics clean, polycrystalline rhenium at...