Reactive dc sputtered tio2 electron transport layers for cadmium‐free sb2se3 solar cells

HIGHLIGHTS

• What: These previous reports, along with the present study, suggest the barrier to electron transport can be mediated by optimized TiO2 processing, provided sufficiently high electron conductivities and low interfacial defect densities can be obtained. The authors report a simple, scalable, reproducible method of preparing highly crystalline wide bandgap anataseTiO2 thin films for application as the ETL in Sb2 Se3 solar cells.
• Who: Christopher H. Don and colleagues from the JE. N. Swallow Department of Materials University of Oxford Parks Road, Oxford , PH, UK L. Bowen Department of Physics University of Durham Durham , LE, UK D. F. Fernandes, T. Kubart Department of Electrical Engineering Division of Solid-State Electronics The Ångström Laboratory Uppsala University , Uppsala, Sweden D. Biswas, P. K. Thakur, T.-L. Lee Diamond Light Source Ltd, Diamond House Harwell Science and Innovation Campus Didcot, Oxfordshire , DE, UK have published the research: Reactive DC Sputtered TiO2 Electron Transport Layers for Cadmium‐Free Sb2Se3 Solar Cells, in the Journal: (JOURNAL)

SUMMARY

The development of thin-film photovoltaics (PV) has led to the commercialization of polycrystalline cadmium telluride (CdTe)- Adv. Energy Mater. In the aforementioned study, Sb2 Se3 solar cells with radio frequency (RF) magnetron sputtered TiO2 ETLs were deposited from a compound TiO2 target, although optimization efforts in this case were limited by reproducibility issues. An SnO2:F/TiO2 /Sb2 Se3 /P3HT/Au device fabricated with a reactively sputtered TiO2 ETL achieved an improved 8.12% 𝜂 due to significantly reduced series resistance (Rs ) compared to similar device structures. Differences in the TiO2 films obtained from both precursor solution and sputtering are compared and discussed in the context of FF variance in completed TiO2 /Sb2 Se3 devices. In summary, the authors have investigated the relationship between TiO2 thin-film fabrication conditions and the performance of subsequent Sb2 Se3 photovoltaic devices with TiO2 acting as an ETL. The effects of varying the μe, ND and surface acceptor-type defect density of TiO2 on device performance are investigated through device modeling simulations which infer the presence of a spike-like CBO between Sb2 Se3 and TiO2. The result provides a robust explanation for FF variability in Sb2 Se3 devices fabricated with TiO2 ETLs, and highlights the ETL parameters most critical for developing high-performance cadmium-free devices. The HiPIMS TiO2 films were fabricated by High Power Impulse Magnetron Sputtering in a Lesker CMS18 deposition system by reactive magnetron sputtering from a Ti target (4N purity) with 100 mm diameter. Prior to Sb2 Se3 deposition, the TiO2 films were ozone-cleaned for 15 min. @@

LAY DEFINITIONS

• Solar cell: A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light
• Binding energy: Binding energy is the energy required to disassemble a whole system into separate parts. A bound system typically has a lower potential energy than the sum of its constituent parts; this is what keeps the system together
• Grazing incidence: In geometric optics, the angle of incidence is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal. The ray can be formed by any wave: optical, acoustic, microwave, X-ray and so on
• Valence band: In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level and thus determine the electrical conductivity of the solid. In non-metals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states
• Scanning electron microscopy: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons
• Photovoltaics: Photovoltaics covers the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. A typical photovoltaic system employs solar panels, each comprising a number of solar cells, which generate electrical power
• Radio frequency: Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves
• Cells: The fundamental, structural, and functional units or subunits of living organisms. They are composed of CYTOPLASM containing various ORGANELLES and a CELL MEMBRANE boundary
• Energy dispersive x-ray spectroscopy: The spectrometric analysis of fluorescent X-RAYS, i.e. X-rays emitted after bombarding matter with high energy particles such as PROTONS; ELECTRONS; or higher energy X-rays
• Titanium isopropoxide: Titanium isopropoxide, also commonly referred to as titanium tetraisopropoxide or TTIP, is a chemical compound with the formula Ti{OCH(CH3)2}4. This alkoxide of titanium(IV) is used in organic synthesis and materials science
• Transport: Transport, or transportation, is the movement of humans, animals and goods from one location to another. In other words, the action of transport is defined as a particular movement of an organism or thing from a point A to a point B
• X-ray diffraction: X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal

Licence: cc-by

Site reference: https://durham-repository.worktribe.com/preview/2484013/2483999AOV.pdf

DOI reference: https://www.doi.org/10.1002/aenm.202401077

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