Optical and electrical properties of solution processable TiOx thin films for solar cell and sensor applications

2011 ◽  
Vol 1352 ◽  
Author(s):  
Jiguang Li ◽  
Lin Pu ◽  
Mool C. Gupta

ABSTRACTRecently, few tens of nanometer thin films of TiOx have been intensively studied in applications for organic solar cells as optical spacers, environmental protection and hole blocking. In this paper we provide initial measurements of optical and electrical properties of TiOx thin films and it’s applications in solar cell and sensor devices. The TiOx material was made through hydrolysis of the precursor synthesized from titanium isopropoxide, 2-methoxyethanol, and ethanolamine. The TiOx thin films of thickness between 20 nm to 120 nm were obtained by spin coating process. The refractive index of TiOx thin films were measured using an ellipsometric technique and an optical reflection method. At room temperature, the refractive index of TiOx thin film was found to be 1.77 at a wavelength of 600 nm. The variation of refractive index under various thermal annealing conditions was also studied. The increase in refractive index with high temperature thermal annealing process was observed, allowing the opportunity to obtain refractive index values between 1.77 and 2.57 at a wavelength 600 nm. The refractive index variation is due to the TiOx phase and density changes under thermal annealing.The electrical resistance was measured by depositing a thin film of TiOx between ITO and Al electrode. The electrical resistivity of TiOx thin film was found to be 1.7×107 Ω.cm as measured by vertical transmission line method. We have also studied the variation of electrical resistivity with temperature. The temperature coefficient of electrical resistance for 60 nm TiOx thin film was demonstrated as - 6×10-3/°C. A linear temperature dependence of resistivity between the temperature values of 20 – 100 °C was observed.The TiOx thin films have been demonstrated as a low cost solution processable antireflection layer for Si solar cells. The results indicate that the TiOx layer can reduce the surface reflection of the silicon as low as commonly used vacuum deposited Si3N4 thin films.

Author(s):  
Abdullah Almohammedi ◽  
Yasser Abdelrady Masoud Ismail ◽  
Mohd Taukeer Khan ◽  
Mohamed Benghanem ◽  
Saleh N Alamri ◽  
...  

Abstract In the present work, a thin film of tin (Sn) metal, instead of aluminum, was deposited as a back electrode, using thermal evaporation, for fabricating organic solar cell composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM). The effect of post-thermal annealing on performance parameters of the solar cell has been investigated at low temperatures (suitable for organic solar cells) up to 180 oC. In addition, effect of thermal annealing on morphological (using scanning electron microscopy) and electrical properties (using Hall Effect setup) of the Sn thin films was reported and discussed here. The obtained minor effect of the thermal annealing on morphological and electrical properties of Sn thin films is offset by an improvement in the performance parameters of solar cells after post-annealing at 160 oC. The present study shows good electrical properties of the Sn thin films which are comparable with those of aluminum thin films.


2020 ◽  
Vol 34 (08) ◽  
pp. 2050068
Author(s):  
Mai Thi Kieu Lien ◽  
Noritaka Usami

We have grown orthorhombic barium disilicide ([Formula: see text]) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time [Formula: see text] on crystalline quality as well as optical and electrical properties of the [Formula: see text] films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the [Formula: see text] thin-films. The [Formula: see text] of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the [Formula: see text] film at [Formula: see text] of 8 s were [Formula: see text], [Formula: see text], and [Formula: see text]s, respectively. These results confirm that the [Formula: see text] thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.


2013 ◽  
Vol 832 ◽  
pp. 404-409 ◽  
Author(s):  
Fazlinashatul Suhaidah Zahid ◽  
Puteri Sarah Mohamad Saad ◽  
Mohamad Rusop Mahmood

In recent years, the research on organic solar cells systems based on nanocomposite containing conjugated polymers has lead to great attention with the aim or replacing conventional inorganic solar cells. This nanocomposite can be processed at lower cost, low weight and ease of synthesis with greater versatility than todays solar cell. In this study, we investigated the dependence of physical, optical and electrical properties on the thickness of MEH-PPV: TiO2 nanocomposite thin films for organic solar cell application. It was found the optical properties of photo-active layer MEH-PPV: TiO2 nanocomposite thin films improved with increasing its thickness however the electrical properties decreased. The absorption coefficients of photoactive layer are high in the visible region (400-600 nm) with optimum absorption region at 500 nm. The shift of absorption edge toward longer wavelength with increased of nanocomposite photoactive layer thickness due to narrowing band gap caused by the effects of electron-electron and electron-impurity scattering. In addition the study of illuminated current-voltage (I-V) characteristics revealed the increment of recombination process with increased of photoactive layer thicknesses. It was found such increased in resistivity from 136x103 to 1600x103 Ω.cm is closely related to the electric field and exciton dissociation which is decreased with increased photoactive thickness.


2011 ◽  
Vol 04 (04) ◽  
pp. 401-405 ◽  
Author(s):  
W. CHER ◽  
S. YICK ◽  
S. XU ◽  
Z. J. HAN ◽  
K. OSTRIKOV

Al -doped zinc oxide (AZO) thin films are deposited onto glass substrates using radio-frequency reactive magnetron sputtering and the improvements in their physical properties by post-synthesis thermal treatment are reported. X-ray diffraction spectra show that the structure of films can be controlled by adjusting the annealing temperatures, with the best crystallinity obtained at 400°C under a nitrogen atmosphere. These films exhibit improved quality and better optical transmittance as indicated by the UV-Vis spectra. Furthermore, the sheet resistivity is found to decrease from 1.87 × 10-3 to 5.63 × 10-4Ω⋅cm and the carrier mobility increases from 6.47 to 13.43 cm2 ⋅ V-1 ⋅ s-1 at the optimal annealing temperature. Our results demonstrate a simple yet effective way in controlling the structural, optical and electrical properties of AZO thin films, which is important for solar cell applications.


2021 ◽  
Vol 902 ◽  
pp. 65-70
Author(s):  
Samar Aboulhadeed ◽  
Mohsen Ghali ◽  
Mohamad M. Ayad

We report on a development of the structural, optical and electrical properties of poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS) conducting polymer thin films. The PEDOT:PSS thin films were deposited by a controlled thin film applicator and their physical properties were found to be effectively modified by isopropanol. The deposited films were investigated by several techniques including XRD, UV–Vis, SPM and Hall-effect. Interestingly, by optimizing the PEDOTS:PSS/ISO volume ratio (v:v), we find that the film charge carriers type can be switched from p to n-type with a high bulk carriers concentration reaching 6×1017 cm-3. Moreover, the film surface roughness becomes smoother and reaching a small value of only 1.9 nm. Such development of the PEDOT:PSS film properties makes it very promising to act as an electron transport layer for different energy applications.


Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1970 ◽  
Author(s):  
Donghyeon Ryu ◽  
Alfred Mongare

In this study, a flexible strain sensor is devised using corrugated bilayer thin films consisting of poly(3-hexylthiophene) (P3HT) and poly(3,4-ethylenedioxythiophene)-polystyrene(sulfonate) (PEDOT:PSS). In previous studies, the P3HT-based photoactive non-corrugated thin film was shown to generate direct current (DC) under broadband light, and the generated DC voltage varied with applied tensile strain. Yet, the mechanical resiliency and strain sensing range of the P3HT-based thin film strain sensor were limited due to brittle non-corrugated thin film constituents. To address this issue, it is aimed to design a mechanically resilient strain sensor using corrugated thin film constituents. Buckling is induced to form corrugation in the thin films by applying pre-strain to the substrate, where the thin films are deposited, and releasing the pre-strain afterwards. It is known that corrugated thin film constituents exhibit different optical and electronic properties from non-corrugated ones. Therefore, to design the flexible strain sensor, it was studied to understand how the applied pre-strain and thickness of the PEDOT:PSS conductive thin film affects the optical and electrical properties. In addition, strain effect was investigated on the optical and electrical properties of the corrugated thin film constituents. Finally, flexible strain sensors are fabricated by following the design guideline, which is suggested from the studies on the corrugated thin film constituents, and the DC voltage strain sensing capability of the flexible strain sensors was validated. As a result, the flexible strain sensor exhibited a tensile strain sensing range up to 5% at a frequency up to 15 Hz with a maximum gauge factor ~7.


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