A5024032759- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Semiconductor materials and interfaces
- Advanced Semiconductor Detectors and Materials
- Phase-change materials and chalcogenides
- Advanced Thermoelectric Materials and Devices
- ZnO doping and properties
- Perovskite Materials and Applications
- 2D Materials and Applications
- Metal Extraction and Bioleaching
- solar cell performance optimization
- Silicon and Solar Cell Technologies
- Calibration and Measurement Techniques
- Ga2O3 and related materials
- nanoparticles nucleation surface interactions
- Semiconductor Quantum Structures and Devices
- Electrocatalysts for Energy Conversion
- Electronic and Structural Properties of Oxides
- Fuel Cells and Related Materials
- Advanced Image Fusion Techniques
- Heusler alloys: electronic and magnetic properties
- Geophysics and Gravity Measurements
- Catalytic Processes in Materials Science
- Transition Metal Oxide Nanomaterials
Tallinn University of Technology
2015-2024
City University of New York
2011
Abstract Cu 2 Zn 1– x Cd Sn(Se y S ) 4 monograin powders with different ‐ and ‐values were prepared from binary compounds in the liquid phase of flux material (KI) evacuated quartz ampoules. All materials had uniform composition p‐type conductivity. PL spectra (10 K) as grown Sn(Se) showed one band peak position around 0.85 eV which shifted linearly to lower energy side increasing content. ZnSnS asymmetrical at 1.31 attributed band‐to‐tail recombination. RT Raman ZnSnSe revealed two main...
In this study, we investigated the photoluminescence (PL) properties of Cu2ZnSnS4 polycrystals. Two PL bands at 1.27 eV and 1.35 T = 10 K were detected. Similar behaviour with temperature excitation power was found for both attributed to band-to-impurity recombination. Interestingly, thermal activation energies determined from dependence coincide. With support Raman results, propose that observed arise band-to-impurity-recombination process involving same deep acceptor defect ionization...
Cu2ZnSnSe4 thin films, fabricated on bare or molybdenum coated glass substrates by magnetron sputtering and selenisation, were studied a range of techniques. Photoluminescence spectra reveal an excitonic peak two phonon replicas donor-acceptor pair (DAP) recombination. Its acceptor donor ionisation energies are 27 7 meV, respectively. This demonstrates that high-quality films can be fabricated. An experimental value for the longitudinal optical energy 28 meV was estimated. The band gap 1.01...
Abstract Kesterite Cu 2 ZnSn(S x Se 1- ) 4 (CZTSSe) semiconductor materials have been extensively studied over the past decade, however despite significant efforts, open circuit voltage remains below 60% of theoretical maximum. Understanding optical and electrical properties is critical to explaining solving deficit. This review aims summarize present knowledge kesterites specifically focuses on experimental data intrinsic defects, charge carrier density transport, minority lifetime related...
Due to the harsh conditions of space, detectors within satellite-based multispectral imagers are always at risk damage or failure. In particular, 15 out 20 that produce 1.6- μm band 6 Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua either dead noisy. this paper, we describe a quantitative image restoration (QIR) algorithm is able accurately estimate and restore data lost due multiple-detector The small number functioning used train function based multivariate regression using...
Abstract In this study, an in-depth photoluminescence (PL) analysis of Cu2GeS3 microcrystals under pulsed and continuous-wave (CW) excitation is performed to explore the optical properties defect structure promising novel absorber material for indoor photovoltaics. A rich low temperature (T = 8 K) PL spectra with multipl- e peaks was detected by both sources analyzed in detail. The edge emission, including free bound excitons as well unique trion emission at 1.575 eV, which becomes dominant...
The energy band structure of Cu2SnS3 (CTS) thin films fabricated by pulsed laser deposition was studied photoreflectance spectroscopy (PR). temperature-dependent PR spectra were measured in the range T = 10–150 K. According to Raman scattering analysis, monoclinic crystal (C1c1) prevails CTS film; however, a weak contribution from cubic (F-43m) also detected. revealed valence splitting CTS. Optical transitions at EA 0.92 eV, EB 1.04 and EC 1.08 eV found for low-temperature (T 10 K)....
Abstract The power conversion efficiency of Cu 2 ZnSnS 4 (CZTS) solar cells is still limited by deep defects, low minority carrier lifetime and high recombination rates at the CZTS/CdS interface. objective this study was to find an effective method reduce interface CZTS monograin layer cells. A two-step heterojunction formation process applied controlling intermixing Cd in interface, which resulted improved device up 11.7%. Surface analysis x-ray photoelectron spectroscopy confirmed...
In this report Cu2ZnSnS4 (CZTS) monograin layer (MGL) solar cells were studied using admittance spectroscopy (AS) (frequency range 20Hz-10 MHz) and temperature dependence of quantum efficiency (QE) curves (T=10K-300K). These studies revealed two deep defect states at EA1= 120 meV EA2= 167 meV. The first state was present in different CZTS while the second had somewhat properties cells. QE showed a shift long wavelength edge with increasing by about 110 towards higher energy. possible origin...
The effect of changes in the composition ratios Cu/(Zn+Sn) and Zn/Sn initial precursor mixtures on final properties Cu2ZnSnS4 (CZTS) monograin powders has been investigated. EDX studies revealed that concentration single phase can be changed only from 0.92 to 0.95 1.0 1.03. Raman spectra all showed main peaks around 287, 338, 375 cm-1 characteristic for CZTS materials. Larger deviations stoichiometry results powder crystals with secondary phases, identified as Sn2S3, SnS2, Cu2-xS ZnS. All...
The reported results confirm that the positive effect of Ag in (Cu<sub>1−x</sub>Ag<sub>x</sub>)<sub>1.85</sub>(Zn<sub>0.8</sub>Cd<sub>0.2</sub>)<sub>1.1</sub>SnS<sub>4</sub> MGL solar cells appears only at very low concentrations (<italic>x</italic> ≤ 1%).
Relatively fast achievements in the kesterite solar cell technology have been made over last decade, but experimental efficiency is still ∼13%. One proposed reason an inappropriate band alignment with Cu2ZnSnS4 (CZTS) and CdS that results strong interface recombination losses. Results of this work show temperature duration air annealing CZTS/CdS heterojunction are essential for device performance. Soft slightly improved due to elemental intermixing at interface. On other hand, extended...