The Experts below are selected from a list of 11547 Experts worldwide ranked by ideXlab platform
M Rusop - One of the best experts on this subject based on the ideXlab platform.
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fabrication of an ultraviolet photoconductive sensor using novel nanostructured nanohole enhanced aligned aluminium doped Zinc Oxide nanorod arrays at low immersion times
Sensors and Actuators B-chemical, 2014Co-Authors: Mohamad Hafiz Mamat, Z Khusaimi, M Z Musa, M F Malek, N N Hafizah, M RusopAbstract:Abstract Novel nanostructured thin-film arrays of nanohole-enhanced aligned aluminium (Al)-doped Zinc Oxide (ZnO) nanorods were prepared using sonicated sol–gel and immersion methods for metal–semiconductor–metal (MSM)-type ultraviolet (UV) photoconductive sensor applications. These nanorod arrays were grown on a glass substrate coated with ZnO nanoparticle thin film as a seed layer at immersion times ranging from 10 to 120 min. Notably, the nanoholes appeared on the nanorods after the annealing process due to the evaporation of water and impurities. The photocurrent properties for the Al-doped ZnO nanorod arrays were significantly improved, increasing by more than five-fold compared to the seed layer when the sensor was illuminated with 365 nm UV light at a density of 750 μA/cm2. Interestingly, the highest responsivity using the Al-doped ZnO nanorod arrays was 1350.84 A/W with an improved photocurrent-to-dark current ratio of 22.7, achieved for the samples prepared with a 50 min immersion time and a gap between metal contacts of 0.07 mm. Our results show that high-performance UV photoconductive sensors can be achieved using a novel structure of nanohole-enhanced aligned Al-doped ZnO nanorod arrays prepared at low immersion times which reduces fabrication time and cost.
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fabrication of ultraviolet photoconductive sensor using a novel aluminium doped Zinc Oxide nanorod nanoflake network thin film prepared via ultrasonic assisted sol gel and immersion methods
Sensors and Actuators A-physical, 2011Co-Authors: Mohamad Hafiz Mamat, Z Khusaimi, M Z Musa, M F Malek, M RusopAbstract:Abstract Unique and novel thin films with aluminium (Al)-doped Zinc Oxide (ZnO) nanostructures consisting of nanorod–nanoflake networks were prepared for metal–semiconductor–metal (MSM)-type ultraviolet (UV) photoconductive sensor applications. These nanostructures were grown on a glass substrate coated with a seed layer using a combination of ultrasonic-assisted sol–gel and immersion methods. The synthesised ZnO nanorods had diameters varying from 10 to 40 nm. Very thin nanoflake structures were grown vertically and horizontally on top of the nanorod array. The thin film had good ZnO crystallinity with a root mean square roughness of approximately 13.59 nm. The photocurrent properties for the Al-doped ZnO nanorod–nanoflake thin films were more than 1.5 times greater than those of the seed layer when the sensor was illuminated with 365 nm UV light at a density of 5 mA/cm2. The responsivity of the device was found to be dependent on the bias voltage. We found that similar photocurrent curves were produced over eight cycles, which indicated that the UV sensing capability of the fabricated sensor was highly reproducible. Our results provide a new approach for utilising the novel structure of Al-doped ZnO thin films with a nanorod–nanoflake network for UV sensor applications. To the best of our knowledge, UV photoconductive sensors using Al-doped ZnO thin films with a nanorod–nanoflake network have not yet been reported.
Ralf Heiderhoff - One of the best experts on this subject based on the ideXlab platform.
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suppressed decomposition of organometal halide perovskites by impermeable electron extraction layers in inverted solar cells
Nature Communications, 2017Co-Authors: K. O. Brinkmann, N. Pourdavoud, T. Gahlmann, L Hoffmann, Selina Olthof, Klaus Meerholz, T. Becker, Jie Zhao, Ralf HeiderhoffAbstract:The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of Aluminium-Doped Zinc Oxide and tin Oxide. We evidence tin Oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and—more importantly—it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability. The stability issue of perovskite-based solar cells is in part due to electrode corrosion. Here, Brinkmannet al. develop an impermeable bilayered electron-extraction layer between the active layer and the electrode, suppressing decomposition of the perovskite and preventing corrosion from the inside.
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Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells
Nature Communications, 2017Co-Authors: K. O. Brinkmann, N. Pourdavoud, T. Gahlmann, L Hoffmann, Selina Olthof, T. Hu, Klaus Meerholz, T. Becker, Jian Zhao, Ralf HeiderhoffAbstract:The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of Aluminium-Doped Zinc Oxide and tin Oxide. We evidence tin Oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and—more importantly—it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.
Miro Zeman - One of the best experts on this subject based on the ideXlab platform.
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The role of Oxide interlayers in back reflector configurations for amorphous silicon solar cells
Journal of Applied Physics, 2013Co-Authors: Valeria Demontis, Arno H. M. Smets, Rudi Santbergen, Carla Sanna, Jimmy Melskens, Alfonso Damiano, Miro ZemanAbstract:Thin Oxide interlayers are commonly added to the back reflector of thin-film silicon solar cells to increase their current. To gain more insight in the enhancement mechanism, we tested different back reflector designs consisting of Aluminium-Doped Zinc Oxide (ZnO:Al) and/or hydrogenated silicon Oxide (SiOx:H) interlayers with different metals (silver, aluminium, and chromium) in standard p-i-n a-Si:H solar cells. We use a unique inverse modeling approach to show that in most back reflectors the internal metal reflectance is lower than expected theoretically. However, the metal reflectance is increased by the addition of an Oxide interlayer. Our experiments demonstrate that SiOx:H forms an interesting alternative interlayer because unlike the more commonly used ZnO:Al it can be deposited by plasma-enhanced chemical vapour deposition and it does not reduce the fill factor. The largest efficiency enhancement is obtained with a double interlayer of SiOx:H and ZnO:Al.
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modelling and optimization of a si h solar cells with zno al back reflector
Solar Energy Materials and Solar Cells, 2010Co-Authors: A M K Dagamseh, B Vet, P Sutta, Miro ZemanAbstract:Abstract The introduction of aluminium doped Zinc Oxide (ZnO:Al) as a back reflector is an important part of the light-trapping techniques in present thin-film silicon solar cells. However, the application of the sputtered ZnO:Al at the back contact often results in an S-shaped J – V characteristic and a low fill factor. Using the advanced semiconductor analysis (ASA) simulation program we investigated the origin of the S-shape in the hydrogenated amorphous silicon (a-Si:H) solar cells. We carried out a sensitivity study of ZnO:Al properties and back-contact interface parameters on the performance of a-Si:H solar cells. The simulation results pointed out that the origin of the S-shape in the J – V curve was due to a poor quality of the n-type a-Si:H/ZnO:Al interface and/or a Schottky barrier at the ZnO:Al/metal interface. The simulated S-shape that matched the experimental one resulted from the presence of a high concentration of defects at the n-type a-Si:H/ZnO:Al interface. These defects can be formed during the sputtering of the ZnO:Al film using deposition conditions that favour strong bombardment of the a-Si:H layer. Introduction of a soft deposition start by adapting the sputtering pressure of ZnO:Al resulted in the J – V characteristic without the S-shape. The short-circuit current of the a-Si:H solar cells with ZnO:Al back reflector was enhanced by ∼1.3 mA/cm 2 and the relative increase in the conversion efficiency was 10%.
Armin G Aberle - One of the best experts on this subject based on the ideXlab platform.
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wet chemical surface texturing of sputter deposited zno al films as front electrode for thin film silicon solar cells
International Journal of Photoenergy, 2015Co-Authors: Xia Yan, Selvaraj Venkataraj, Armin G AberleAbstract:Transparent conductive Oxides (TCOs) play a major role as the front electrodes of thin-film silicon (Si) solar cells, as they can provide optical scattering and hence improved photon absorption inside the devices. In this paper we report on the surface texturing of Aluminium-Doped Zinc Oxide (ZnO:Al or AZO) films for improved light trapping in thin-film Si solar cells. The AZO films are deposited onto soda-lime glass sheets via pulsed DC magnetron sputtering. Several promising AZO texturing methods are investigated using diluted hydrochloric (HCl) and hydrofluoric acid (HF), through a two-step etching process. The developed texturing procedure combines the advantages of the HCl-induced craters and the smaller and jagged—but laterally more uniform—features created by HF etching. In the two-step process, the second etching step further enhances the optical haze, while simultaneously improving the uniformity of the texture features created by the HCl etch. The resulting AZO films show large haze values of above 40%, good scattering into large angles, and a surface angle distribution that is centred at around 30°, which is known from the literature to provide efficient light trapping for thin-film Si solar cells.
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modified surface texturing of aluminium doped Zinc Oxide azo transparent conductive Oxides for thin film silicon solar cells
Energy Procedia, 2013Co-Authors: Selvaraj Venkataraj, Armin G AberleAbstract:Abstract For thin-film solar cells, the properties of the front transparent conductive Oxide (TCO) electrode is an important factor in determining the overall performance of the solar cells. An efficient light trapping scheme is required to increase the optical light path and thus enhance the photon absorption within the solar cells. Improved photon absorption is necessary to increase the short-circuit current density ( Jsc ) and thus the efficiency of cells. In this paper we report the results of the texturing of Aluminium-Doped Zinc Oxide (ZnO:Al or AZO) thin films for enhanced light scattering. AZO films were deposited onto soda-lime glass sheets by in-line DC magnetron sputtering. An effective AZO texturing method was developed using diluted hydrogen chloride (HCl) and hydrogen fluoride (HF) acids through either a two-step etching or a mixed etching process, which significantly improves the uniformity of the textured surface. Texturing based on HCl and HF combines the advantages of the large craters created by HCl etching and smaller jagged but uniform features resulting from HF etching. In this work, we demonstrate that by adopting the two-step or the mixed texturing method, it is possible to achieve high haze values of above 40% with very low surface roughness values. The combination of low surface roughness and high haze is beneficial to prevent shunting issues, and is thus very attractive for the fabrication of thin-film silicon solar cells.
Mohamad Hafiz Mamat - One of the best experts on this subject based on the ideXlab platform.
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fabrication of an ultraviolet photoconductive sensor using novel nanostructured nanohole enhanced aligned aluminium doped Zinc Oxide nanorod arrays at low immersion times
Sensors and Actuators B-chemical, 2014Co-Authors: Mohamad Hafiz Mamat, Z Khusaimi, M Z Musa, M F Malek, N N Hafizah, M RusopAbstract:Abstract Novel nanostructured thin-film arrays of nanohole-enhanced aligned aluminium (Al)-doped Zinc Oxide (ZnO) nanorods were prepared using sonicated sol–gel and immersion methods for metal–semiconductor–metal (MSM)-type ultraviolet (UV) photoconductive sensor applications. These nanorod arrays were grown on a glass substrate coated with ZnO nanoparticle thin film as a seed layer at immersion times ranging from 10 to 120 min. Notably, the nanoholes appeared on the nanorods after the annealing process due to the evaporation of water and impurities. The photocurrent properties for the Al-doped ZnO nanorod arrays were significantly improved, increasing by more than five-fold compared to the seed layer when the sensor was illuminated with 365 nm UV light at a density of 750 μA/cm2. Interestingly, the highest responsivity using the Al-doped ZnO nanorod arrays was 1350.84 A/W with an improved photocurrent-to-dark current ratio of 22.7, achieved for the samples prepared with a 50 min immersion time and a gap between metal contacts of 0.07 mm. Our results show that high-performance UV photoconductive sensors can be achieved using a novel structure of nanohole-enhanced aligned Al-doped ZnO nanorod arrays prepared at low immersion times which reduces fabrication time and cost.
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fabrication of ultraviolet photoconductive sensor using a novel aluminium doped Zinc Oxide nanorod nanoflake network thin film prepared via ultrasonic assisted sol gel and immersion methods
Sensors and Actuators A-physical, 2011Co-Authors: Mohamad Hafiz Mamat, Z Khusaimi, M Z Musa, M F Malek, M RusopAbstract:Abstract Unique and novel thin films with aluminium (Al)-doped Zinc Oxide (ZnO) nanostructures consisting of nanorod–nanoflake networks were prepared for metal–semiconductor–metal (MSM)-type ultraviolet (UV) photoconductive sensor applications. These nanostructures were grown on a glass substrate coated with a seed layer using a combination of ultrasonic-assisted sol–gel and immersion methods. The synthesised ZnO nanorods had diameters varying from 10 to 40 nm. Very thin nanoflake structures were grown vertically and horizontally on top of the nanorod array. The thin film had good ZnO crystallinity with a root mean square roughness of approximately 13.59 nm. The photocurrent properties for the Al-doped ZnO nanorod–nanoflake thin films were more than 1.5 times greater than those of the seed layer when the sensor was illuminated with 365 nm UV light at a density of 5 mA/cm2. The responsivity of the device was found to be dependent on the bias voltage. We found that similar photocurrent curves were produced over eight cycles, which indicated that the UV sensing capability of the fabricated sensor was highly reproducible. Our results provide a new approach for utilising the novel structure of Al-doped ZnO thin films with a nanorod–nanoflake network for UV sensor applications. To the best of our knowledge, UV photoconductive sensors using Al-doped ZnO thin films with a nanorod–nanoflake network have not yet been reported.