Vision-driven Autocharacterization of Perovskite Semiconductors

In materials research, the task of characterizing hundreds of different materials traditionally requires equally many human hours spent measuring samples one by one. We demonstrate that with the integration of computer vision into this material research workflow, many of these tasks can be automated, significantly accelerating the throughput of the workflow for scientists. We present a framework that uses vision to address specific pain points in the characterization of perovskite semiconductors, a group of materials with the potential to form new types of solar cells. With this approach, we automate the measurement and computation of chemical and optoelectronic properties of perovskites. Our framework proposes the following four key contributions: (i) a computer vision tool for scalable segmentation to arbitrarily many material samples, (ii) a tool to extract the chemical composition of all material samples, (iii) an algorithm capable of automatically computing band gap across arbitrarily many unique samples using vision-segmented hyperspectral reflectance data, and (iv) automating the stability measurement of multi-hour perovskite degradation experiments with vision for spatially non-uniform samples. We demonstrate the key contributions of the proposed framework on eighty samples of unique composition from the formamidinium-methylammonium lead tri-iodide perovskite system and validate the accuracy of each method using human evaluation and X-ray diffraction.Comment: Manuscript 8 pages; Supplemental 7 page

Silisyum bileşiklerinin bilgisayar destekli INFRARED (IR) analizi

TEZ1596Tez (Doktora) -- Çukurova Üniversitesi, Adana, 1994.Kaynakça (s. 102-105) var.vi, 107 s. ; 30 cm.…Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi Tarafından Desteklenmiştir

Structural Properties and Electrical Characteristics of p-n Junctions Based on Kesterite Cu2ZnSnS4 Layers for Thin-Film Solar Cells

In the present study, we provide useful data related to one of the most promising materials in thin-film solar cell technologies: Cu2ZnSnS4 (CZTS) kesterite structures. Sol-gel spin coating and chemical bath deposition methods were used to fabricate and further investigate Mo/CZTS/CdS/ZnO/AZO heterostructures. In order to examine the crystal structure of the samples, Raman scattering measurements using two excitation wavelengths (514.5 nm and 785 nm) were performed. Three Raman bands related to CZTS were found, as well as one that had its origin in CdS. By using laser ablation and performing Raman spectroscopy on these modified samples, it was shown that during the manufacturing process a MoS2 interlayer was formed between the CZTS and Mo layers. Our method proved that the CZTS layer in a multilayer device structure fabricated by solution-based methods can be decomposed, and thus a detailed analysis of the layer can be performed. Subsequently, current-voltage curves were investigated in terms of the essential electrical properties of glass/Mo/p-CZTS/n-CdS/ZnO/AZO junctions and occurring current transport mechanisms. Finally, AFM data were acquired to study the surface topography of the studied samples. The images showed that these surfaces had a uniform grain structure

Dependence of film thickness on the structural and optical properties of ZnO thin films

WOS: 000264408000027ZnO thin films are prepared on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) at room temperature. Optical parameters such as optical transmittance, reflectance, band tail, dielectric coefficient, refractive index, energy band gap have been studied, discussed and correlated to the changes with film thickness. Kramers-Kronig and dispersion relations were employed to determine the complex refractive index and dielectric constants using reflection data in the ultraviolet-visible near infrared regions. Films with optical transmittance above 90% in the visible range were prepared at pressure of 6.5 x 10(4) Torr. XRD analysis revealed that all films had a strong ZnO (0 0 2) peak, indicating c-axis orientation. The crystal grain size increased from 14.97 nm to 22.53 nm as the film thickness increased from 139 nm to 427 nm, however no significant change was observed in interplanar distance and crystal lattice constant. Optical energy gap decreased from 3.21 eV to 3.19 eV with increasing the thickness. The transmission in UV region decreased with the increase of film thickness. The refractive index, Urbach tail and real part of complex dielectric constant decreased as the film thickness increased. Oscillator energy of as-deposited films increased from 3.49 eV to 4.78 eV as the thickness increased. (C) 2009 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [106T613]This work was supported by the Scientific and Technological Research Council of Turkey under Grant No 106T613. The author would like to thank H. Karaagac, for the XRD analysis

Effect of the oxidation temperature on microstructure and conductivity of ZnxNy thin films and their conversion into p-type ZnO:N films

Transparent p-type ZnO:N thin films have been fabricated by the oxidation of n-type ZnxNy films. The ZnxNy thin films on glass substrate were deposited by pulsed filtered cathodic vacuum arc deposition using metallic zinc (99.999%) as a cathode target in pure nitrogen plasma. The properties of the films were examined after oxidation between 350 and 550 degrees C in air atmosphere. The atomic force microscopy (AFM) analysis revealed that the surface morphology was smooth. As-deposited ZnxNy films were opaque and conductive (rho = 4.36 x 10(-3) Omega cm, N-D = 7.70 x 1021 cm(2)/Vs) due to excess of Zn in the structure. After oxidation between 350 and 500. C, p-type ZnO:N thin films were obtained. The lowest resistivity of 44.50 Omega cm with a hole concentration and Hall mobility of 2.08 x 10(17) cm(-3) and 0.673 cm(2)/Vs, respectively, was obtained after oxidation at 450 degrees C. However, when the oxidation temperature reached to 550 degrees C, the conduction type of the ZnO: N film was changed from p-type to n-type. X-ray photoemission spectroscopy (XPS) analysis confirmed the formation of Zn-N bonds and substitution incorporation of oxygen for nitrogen on the surface of the film. Besides, with a further increase of oxidation temperature to 550 degrees C, the decrease of N concentration in the sample was also confirmed by XPS analysis. (C) 2013 Elsevier B.V. All rights reserved

CHARACTERIZATION OF n AND p TYPE ZNO THIN FILMS DEPOSITED BY CATHODIC PULSED FILTERED VACUUM ARC SYSTEM

The transparent, conductive n and p-type semiconducting ZnO thin films were prepared by pulsed filtered cathodic vacuum arc deposition (PFCVAD) method. The structural, optical and electrical properties of n and p-type ZnO thin films are investigated after annealing at 450 degrees C. 197 nm thick ntype ZnO thin film was deposited with oxygen pressure of 8.5x10(-4) Torr. XRD pattern of annealed ZnO thin film exhibits hexagonal structure with (100), (101) and (110) orientations. The crystallite size of semiconductor ZnO thin film is 18 nm, interplanar distance 0.16 nm and lattice constant c is 0.52 nm for (110) orientation. The optical transmittance spectra of n and p-type ZnO films are over 90% in the visible wavelength region with optical energy gap 3.3 eV. p-type ZnO thin films are produced by oxidation of PFCVAD deposited zinc nitride. Zinc nitride is deposited with nitrogen pressure of 8.6x10(-4) Torr and the thickness of this film is 179 nm. The oxidation of zinc nitride thin films at 450 degrees C results in hexagonal structures p-type ZnO thin films. XRD pattern of this film has the same (100), (101) and (110) orientations with the same crystalline structures as the directly deposited ZnO thin film. Hall measurements indicated that ZnO films were p-type and the highest carrier concentration of 1.08x10(18) cm(-3) and mobility of 93.53 cm(2)/Vs were obtained

Structural, optical and electrical properties of N-doped ZnO thin films prepared by thermal oxidation of pulsed filtered cathodic vacuum arc deposited ZnxNy films

In this study, N-doped ZnO thin films were fabricated by oxidation of ZnxNy films. The ZnxNy thin films were deposited on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) using metallic zinc wire (99.999%) as a cathode target in pure nitrogen plasma. The influence of oxidation temperature, on the electrical, structural and optical properties of N-doped ZnO films was investigated. P-type conduction was achieved for the N-doped ZnO obtained at 450 degrees C by oxidation of ZnxNy, with a resistivity of 16.1 Omega cm, hole concentration of 2.03 x 10(16) cm(-3) and Hall mobility of 19 cm(2)/Vs. X-ray photoelectron spectroscopy (XPS) analysis confirmed the incorporation of N into the ZnO films. X-ray diffraction (XRD) pattern showed that the films as-deposited and oxidized at 350 degrees C were amorphous. However, the oxidized films in air atmosphere at 450-550 degrees C were polycrystalline without preferential orientation. In room temperature photoluminescence (PL) spectra, an ultraviolet (UV) peak was seen for all the samples. In addition, a broad deep level emission was observed. (C) 2011 Elsevier B. V. All rights reserved

Vision-driven Autocharacterization of Perovskite Semiconductors

In materials research, the task of characterizing hundreds of different materials traditionally requires equally many human hours spent measuring samples one by one. We demonstrate that with the integration of computer vision into this material research workflow, many of these tasks can be automated, significantly accelerating the throughput of the workflow for scientists. We present a framework that uses vision to address specific pain points in the characterization of perovskite semiconductors, a group of materials with the potential to form new types of solar cells. With this approach, we automate the measurement and computation of chemical and optoelectronic properties of perovskites. Our framework proposes the following four key contributions: (i) a computer vision tool for scalable segmentation to arbitrarily many material samples, (ii) a tool to extract the chemical composition of all material samples, (iii) an algorithm capable of automatically computing band gap across arbitrarily many unique samples using vision-segmented hyperspectral reflectance data, and (iv) automating the stability measurement of multi-hour perovskite degradation experiments with vision for spatially non-uniform samples. We demonstrate the key contributions of the proposed framework on eighty samples of unique composition from the formamidinium-methylammonium lead tri-iodide perovskite system and validate the accuracy of each method using human evaluation and X-ray diffraction