Ismael Cosme

National Institute of Astrophysics, Optics and Electronics | INAOE · Optics Coordination

In this work, we present the innovative synthesis of salophen (acetaminosalol) derivatives in a solvent-free environment by high-speed ball milling, using a non-conventional activation method, which allowed obtaining compounds in a shorter time and with a better yield. Furthermore, for the first time, the salophen derivatives were deposited as comp...

This study employed time-of-flight secondary ion mass spectrometry (TOF-SIMS) to investigate degradation pathways at the nanoscale, utilizing its capacity for in-depth chemical and structural analysis through various methods, including depth profiling and 3D analysis. A key focus is the matrix effect in ToF-SIMS, which alters secondary ion yields b...

This study focuses on investigating interfaces in perovskite solar cells (PSCs) fabricated by using two different deposition methods. One structure involves all-solution processing, with the photoactive layer spin-coated, and organic semiconductors for the hole and electron transporting layers (HTL and ETL). The other structure incorporates inorgan...

The goal of this work is to study the effect of annealing temperature Ta on the properties of CH3NH3PbI3 (MAPI) thin films deposited on glass substrate through structural, compositional, and optical characterization. The films were obtained by one-step deposition method in which an anti-solvent drip was implemented with some delay during spin coati...

In this work, we study doping-free hybrid heterojunction interfaces based on silicon, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) and conjugated polyelectrolyte poly [(9,9-bis(3′-(N, N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene) (PFN). For this, three types of hybrid structures were fabricated: a sin...

The influence of the composition of silicate glass substrates on the properties of MAPI (CH3NH3PbI3) films with a 1:1:1 % mol ratio of MAI:PbI2:DMSO, deposited by Spin-Coating at 4000 rpm for 30 seconds, was studied. X-ray diffraction suggested the presence of the tetragonal phase and a secondary PbI 2 phase. By SEM and AFM grain sizes between 100...

Enhanced transparency, conductivity, and stability are some of the most important factors to consider in order to prepare transparent electrodes (TEs) and hole transport layer (HTL) for organic solar cells. In this study, the transparency, optical, and electrical behavior of hybrid films formed by poly(3,4-ethylenedioxythiophene):poly (styrenesulfo...

The detection scheme based on phase detection of SPR response was developed. We show that the proposed biosensing scheme can detect SARS-CoV-2 genetic material with high specificity, low detection limit and short detection time.

In this work, innovative composite films were deposited using as a matrix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and particles of difluoroboron β-diketonate complexes, with different substituents in their periphery as a reinforcement. The composite films were treated with isopropanol (IPA) steam, with the purpose of decr...

The use of composite films with semiconductor behavior is an alternative to enhance the efficiency of optoelectronic devices. Composite films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and metalloporphines (MPs; M = Co, Cu, Pd) have been prepared by spin-coating. The PEDOT:PSS-MP films were treated with isopropanol (IPA)...

Introduction. PECVD enables fabrication of wide range of advanced materials with various structure such as amorphous, polymorphous, nano-crystalline, nanostructured, microcrystalline etc. and with various electronic properties. The latter can be also changed by different dopingl. PECVD silicon materials are commercially employed in multi-layered PV...

This works refers to the manufacture and characterization of organic electronic devices made from seven-coordinated diorganotin(IV) complexes and the polymer poly(3,4-ethylenedyoxithiophene)-poly(styrene sulfonate) (PEDOT:PSS). In order to obtain the best electronic behavior, the devices were manufactured by spin-coating with seven-coordinated dior...

The formation of superficial nanostructures (SNs) in reduced indium tin oxide (ITO) thin films by H2-Glow discharge (GD) at a low reduction temperature (Tr=100 °C) was investigated. Sputtered ITO films deposited at low (Td=100 °C) and high (Td=300 °C) temperatures were reduced using this low-temperature process. Scanning electron and atomic force m...

In this work, we present the study of the atomic composition in amorphous SiXGeY:HZ films deposited by radio frequency (RF—13.56 MHz) plasma discharge at low deposition temperature. A study and control of Si and Ge atoms termination using H-dilution in SiGe:H alloys deposited by RF plasma discharge was conducted and we made a comparison with low-fr...

A fluorescent pentamer 5QnQnPV with one phenyl central donor group surrounded by four quinoline acceptor groups set in a quadrupolar A-π-A-π-D-π-A-π-A electronic structure was synthesized. This compound is an organic semiconductor and shows a wide band fluorescence emission that spans from the blue to the red region with a maximum peak centered at...

In this work, we propose poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) material to form a hybrid heterojunction with amorphous silicon-based materials for high charge carrier collection at the frontal interface of solar cells. The nanostructural characteristics of PEDOT:PSS layers were modified using post-treatment techniques...

This chapter contains sections titled: Introduction Experimental Material Results Results for Devices Outlook Acknowledgment

Thin-film hybrid organic-inorganic photovoltaic structures based on hydrogenated silicon (Si:H), poly(3,4ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) polymer Al-doped ZnO (AZO) films deposited on different types of flexible substrates have been fabricated and investigated. The compatibility of the polymer and inorganic materials reg...

Esta invención se refiere a un dispositivo fotovoltaico para transformación de luz en energía eléctrica y sus pasos de fabricación de materiales depositados por plasma. El dispositivo está formado por nuevas configuraciones p-i-ATH-i-n o n-i-ATH-i-p doble o triple donde materiales intrínsecos con diferente ancho de banda óptico son organizados de t...

Hybrid thin film photovoltaic structures, based on hydrogenated silicon (Si:H), organic poly(3-hexythiophene):methano-fullerenephenyl-C61-butyric-acid-methyl-ester (P3HT:PCBM) and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films, have been fabricated. Organic semiconductor thin films were deposited by spin-coating techniq...

Indium tin oxide (ITO) thin films were deposited by magnetron sputtering with different oxygen flows rates (%O 2 = 1 % to 0 %). The films were deposited by RF discharge in argon/oxygen atmosphere with a RF power W = 150 W at substrate temperature T = 175° C and pressure P = 6 mTorrs. Photoelectric parameters of fabricated ITO films were characteriz...

We have studied the effect of Ge-concentration in gas phase on electronic properties of Ge X Si Y :H alloys deposited by RF-PECVD. The relative gas phase Ge concentration was varied from [Ge] gas = 50 % to 100 %. The electronic properties of the films were studied by the measurements of temperature dependence of dark conductivity σ dark (T) in the...

Measurements of non-steady-state P-EMF current as a function temporal and spatial modulation frequencies were performed on intrinsic hydrogenated amorphous silicon film at 633 nm wavelength. The experimental behavior of photo-EMF current is well described by a bipolar photoconductivity model. Material photoelectric parameters such as majority carri...

Fabrication of high-quality ultrathin monocrystalline silicon layers and their transfer to low-cost substrates are key steps for flexible electronics and photovoltaics. In this work, we demonstrate a low-temperature and low-cost process for ultrathin silicon solar cells. By using standard plasma-enhanced chemical vapor deposition (PECVD), we grow h...

Temperature dependence of DC conductivity σDC(T) of spin-coated poly (3,4 ethylenedioxythiophene):poly(4- styrenesulfonate) (PEDOT:PSS) films has been studied. σDC(T) was measured in films deposited from mixtures of PEDOT/PSS:H2O (1:0.5), PEDOT:PSS (without dilution), PEDOT/PSS:Isopropyl Alcohol (IPA)(1:0.5) and PEDOT/PSS:IPA (1:1). Room temperatur...

Inorganic-organic hybrid solar cells with different frontal interface configurations have been studied. Spin-coated conducting polymer Poly (3,4 ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) or boron doped a-Si:H films were used as p-type layer. Intrinsic amorphous silicon (a-Si:H) films and P3HT:PCBM heterojunctions were investigat...

Merging photovoltaics with photonics in the past decade has set the path for scaling down the surface texture of crystalline-silicon solar cells from the micro- to the nanoscale, allowing to boost the photon absorption while reducing silicon material loss. However, keeping good electrical performance has proven to be very challenging, as the absorb...

THIN FILM SOLAR CELLS, Silicon-based Thin Film Solar Cells, Epitaxial Growth of Silicon Thin Films by Low Temperature RF-PECVD from SiF4/H2/Ar

Title: Nanophotonics for Ultra-Thin Crystalline Silicon Photovoltaics: When Photons (Actually) Meet Electrons Abstract/Summary: Nanopatterning has recently demonstrated to be an efficient method for boosting the light absorption of thin films (< 50 μm) of crystalline silicon. However, convincing solar cell results are still missing. The goal of...

We report on the fabrication, integration, and simulation, both optical and optoelectrical, of two-dimensional photonic nanostructures for advanced light trapping in thin crystalline silicon (c-Si) solar cells. The photonic nanostructures are fabricated by the combination of various lithography (nanoimprint, laser interference, and hole mask colloi...

Nanopatterning has recently demonstrated to be an efficient method for boosting the light absorption of thin films (< 50 µm) of crystalline silicon. However, convincing solar cell results are still missing. The goal of the European project PhotoNVoltaics is to investigate the impacts that nanopatterns have on thin crystalline silicon solar cells an...

The dark current-voltage characteristics of PIN structures are studied and analyzed for PV samples as for integral device without taking account the performance of the different elements typically used in equivalent circuit model such as diode n-factor, shunt and series resistances. The contribution of all these elements is very important in the de...

In this work we present the results of comparative study n- and p-doping of Ge:H and Ge0.96Si0.04 :H films deposited by LF PECVD at high deposition temperature (HT) Td=300°C and low deposition temperature (LT) Td=160°C. The concentration of boron and phosphorus in solid phase was measured by means of SIMS technique. Such parameters as spectral depe...

This paper reports the study of GeySi1-y:H films deposited at temperatures in the range of Td= 70 to 300 °C. The films were grown in capacitive low-frequency (f=110 KHz) discharge from Si:H4 and Ge:H4 feed gases diluted with H2. Other parameters were as follow: hydrogen flow QH2= 3750 sccm, silane flow QSiH4=50 sccm, germane flow QGeH4= 500 sccm hy...

Ge-Si films deposited by PECVD are very attractive for photo-detector devices because their narrow band gaps allow absorption of longer wavelength than amorphous silicon films do. With their narrow band gap, it is possible making devices such as tandem solar cells with improved long wavelength absorption, photo-detectors suitable for optical commun...

The films studied were grown at the temperature Td= 160 °C and doped by boron (B) and phosphorus (P) by incorporation of diborane (B2H6) and phosphine (PH3), respectively, in gas mixture used for the deposition. For B-doped films changing boron concentration in gas phase CBgas from 0.04% to 0.06%, resulted in changing electrical characteristics: co...

This paper reports the study of GeySi1−y:H films deposited at temperatures in the range of Td= 70 to 300 °C. The films were grown in capacitive low-frequency (f=110 KHz) discharge from Si:H4 and Ge:H4 feed gases diluted with H2. Other parameters were as follow: hydrogen flow QH2= 3750 sccm, silane flow QSiH4=50 sccm, germane flow QGeH4= 500 sccm hy...

Noise spectra in plasma deposited SixGeyBz:H thermo-sensing films for micro-bolometers have been studied. The samples were characterized by SIMS (composition) and conductivity (room temperature conductivity, activation energy) measurements. The noise spectra were measured in the temperature range from T= 300 K to T=400 K and in the frequency range...

Low frequency noise in a-SixGey:H thermo-sensing films, on glass and in micro-bolometers of planar and sandwich structures based on the same material has been studied at different temperatures. The noise spectra had the form of the 1/f-like noise with the frequency exponent within the range of 0.8 to 1.6 depending on the sample and temperature. In...

Noise spectra in plasma deposited SixGeyB z:H thermo-sensing films for micro-bolometers have been studied. The samples were characterized by SIMS (composition) and conductivity (room temperature conductivity, activation energy) measurements. The noise spectra were measured in the temperature range from T= 300 K to T=400 K and in the frequency range...

We have studied noise in four configurations of un-cooled micro-bolometers: three of them were built in a planar structure with a) a-Six Ge y, y = 0.88, b) a-SixGeyBz:H, y = 0.67 and z = 0.26; c) y = 0.71, z = 0.23 and the fourth d) sandwich structure with y = 0.88. These samples were characterized by SIMS (composition), FTIR (H-bonding and H conte...