Insight into Al–Si interface of PERC by Kelvin probe force microscopy

Passivated emitter and rear cell (PERC) has the advantage of higher short circuit current and open circuit voltage, which are generally claimed to be related to the reduction of rear side recombination and the increase of rear surface reflection. However, few works have focused on exploring the internal conducting mechanism about it. Herein, the influence of PERC technique on improving the short circuit current is investigated by comparing a PERC with a single crystalline silicon (sc-Si) solar cell. The surface potential results measured by Kelvin probe force microscopy show a higher surface potential step at the Al–Si interface of PERC than that of sc-Si cell, indicating a severe energy band variation and a better carrier collecting ability of PERC. Moreover, by using advanced microstructure characterization techniques, the relationship among the surface potential step, morphology and element distribution is fully studied, which proposes a new viewpoint to explain the enhanced performance of PERC.

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Measurement of surface potential and adhesion with Kelvin Probe Force Microscopy

2016 International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS) ◽

10.1109/marss.2016.7561734 ◽

2016 ◽

Author(s):

Hao Zhang ◽

Danish Hussain ◽

Xianghe Meng ◽

Jianmin Song ◽

Hui Xie

Keyword(s):

Surface Potential ◽

Kelvin Probe Force Microscopy ◽

Kelvin Probe ◽

Force Microscopy

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Practical Performance Analysis of a Bifacial PV Module and System

Energies ◽

10.3390/en13174389 ◽

2020 ◽

Vol 13 (17) ◽

pp. 4389

Author(s):

Juhee Jang ◽

Kyungsoo Lee

Keyword(s):

Short Circuit ◽

Rear Surface ◽

Short Circuit Current ◽

Specific Yield ◽

Rear Side ◽

Pv System ◽

Pv Module ◽

Pv Modules ◽

Pm 10 ◽

Sky Conditions

Bifacial photovoltaic (PV) modules can take advantage of rear-surface irradiance, enabling them to produce more energy compared with monofacial PV modules. However, the performance of bifacial PV modules depends on the irradiance at the rear side, which is strongly affected by the installation setup and environmental conditions. In this study, we experiment with a bifacial PV module and a bifacial PV system by varying the size of the reflective material, vertical installation, temperature mismatch, and concentration of particulate matter (PM), using three testbeds. From our analyses, we found that the specific yield increased by 1.6% when the reflective material size doubled. When the PV module was installed vertically, the reduction of power due to the shadow effect occurred, and thus the maximum current was 14.3% lower than the short-circuit current. We also observed a maximum average surface temperature mismatch of 2.19 °C depending on the position of the modules when they were composed in a row. Finally, in clear sky conditions, when the concentration of PM 10 changed by 100 µg/m3, the bifacial gain increased by 4%. In overcast conditions, when the concentration of PM 10 changed by 100 µg/m3, the bifacial gain decreased by 0.9%.

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Measurement of electrostatic tip–sample interactions by time-domain Kelvin probe force microscopy

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.11.76 ◽

2020 ◽

Vol 11 ◽

pp. 911-921

Author(s):

Christian Ritz ◽

Tino Wagner ◽

Andreas Stemmer

Keyword(s):

Frequency Shift ◽

Surface Potential ◽

Electrostatic Force ◽

Kelvin Probe Force Microscopy ◽

Kelvin Probe ◽

Force Microscopy ◽

Atomic Force ◽

Alternative Approach ◽

Dc Component ◽

Lock In

Kelvin probe force microscopy is a scanning probe technique used to quantify the local electrostatic potential of a surface. In common implementations, the bias voltage between the tip and the sample is modulated. The resulting electrostatic force or force gradient is detected via lock-in techniques and canceled by adjusting the dc component of the tip–sample bias. This allows for an electrostatic characterization and simultaneously minimizes the electrostatic influence onto the topography measurement. However, a static contribution due to the bias modulation itself remains uncompensated, which can induce topographic height errors. Here, we demonstrate an alternative approach to find the surface potential without lock-in detection. Our method operates directly on the frequency-shift signal measured in frequency-modulated atomic force microscopy and continuously estimates the electrostatic influence due to the applied voltage modulation. This results in a continuous measurement of the local surface potential, the capacitance gradient, and the frequency shift induced by surface topography. In contrast to conventional techniques, the detection of the topography-induced frequency shift enables the compensation of all electrostatic influences, including the component arising from the bias modulation. This constitutes an important improvement over conventional techniques and paves the way for more reliable and accurate measurements of electrostatics and topography.

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