المأساوي بوصفه قيمةً جماليةً

يحاول هذا البحث تقديم رؤية نقدية في القيم الجمالية، ولا يدعي لها أسس النظرية وإنْ كانت قريبة منها، وستقصر اهتمامها على دراسة مصطلح المأساوي بوصفه قيمة جمالية. وقد اتخذ البحث من المنهج الوصفي منطلقاً إجرائياً يسعفه في استقراء الآراء الجمالية النقدية التي تناولها، ومن ثمَّ تصدى بالملاحظة والتحليل والمناقشة لطروحات أهم النقاد الجماليين الذين تناولوا مفهوم المأساوي، وعرض للفرق بين المأساوي والمعذّب، وكذا الفرق بين المأساوي والمأساة، ثم بيّن عناصر المأساوي، وأخيراً صلة المأساوي بالفنون، فعرض لنماذج من الشعر العربي اتخذها نماذج للدراسة في تأكيد رؤيته، وخرج بملاحظات من أهمها أنَّ المأساوية والمأساة أمران متلازمان، نظيرَ ما تتلازم الملحمية والملحمة، والغنائية والقصيدة

Process Development of Silicon Heterojunction Interdigitated Back-Contacted (SHJ-IBC) Solar Cells Bonded to Glass

In imec’s i2-module concept, silicon heterojunction interdigitated back-contacted (SHJ-IBC) solar cells are fabricated on monocrystalline foils bonded to glass. The proposed technology allows for cell processing on thin wafers mechanically supported by the glass, increasing the yield of processing such thin wafers. A process sequence for SHJ-IBC cell fabrication that can be applied to bonded thin foils is described. We investigated and optimized individual process steps on thick wafers. Then the developed steps were integrated into a process flow to fabricate solar cells on wafers with different thicknesses and bonding agents. On wafers with a thickness of 190 μm, functional cells with efficiencies of 22.6% and 21.7% were made on freestanding and silicone bonded wafers, respectively. On thin wafers of 57 μm, our best SHJ-IBC cell on an EVA bonded wafer exhibits excellent Voc of 740 mV and efficiency of 20.0%, which demonstrates the high potential of the i2-module concept

Electro-Physical Interpretation of the Degradation of the Fill Factor of Silicon Heterojunction Solar Cells Due to Incomplete Hole Collection at the a-Si:H/c-Si Thermionic Emission Barrier

An electro-physical interpretation for the degradation of the Fill Factor in p+/n silicon heterojunction solar cells (SHJ) due to incomplete hole collection at the thermionic emission barrier at the amorphous/crystalline silicon (a-Si:H/c-Si) hetero-interface is proposed supported by results of AFORS-HET device simulations. Under illumination, reflected holes at the thermionic barrier pile up at the hetero-interface which strengthens the dipole with the negative dopant ions in the doped a-Si:H(p+) layer and enhances the electric field passing through the a-Si:H layer. Such an enhanced electric field sweeps back the free holes spilling over in the intrinsic a-Si:H(i) layer from the a-Si:H(p+) layer considerably depleting the double a-Si:H layer and enhancing its resistance and the overall cell series resistance. Therefore, the degradation due to incomplete hole collection at the thermionic emission barrier under illumination can be assimilated to the effect of a series resistance does not affect the cell open circuit voltage but degrades only its fill factor. The resistance enhancement is found to be bias-dependent and to increase with decreasing the doping level in a-Si:H(p+). Predictions of the proposed model for different hole reflection probability at the barrier and for different thicknesses of the intrinsic a-Si:H(i) layer agree perfectly with the results of simulations

The Role of Silicon Heterojunction and TCO Barriers on the Operation of Silicon Heterojunction Solar Cells: Comparison between Theory and Experiment

Photovoltaic devices based on amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction interfaces hold the highest efficiency as of date in the class of silicon-based devices with efficiencies exceeding 26% and are regarded as a promising technology for large-scale terrestrial PV applications. The detailed understanding behind the operation of this type of device is crucial to improving and optimizing its performance. SHJ solar cells have primarily two main interfaces that play a major role in their operation: the transparent conductive oxide (TCO)/a-Si:H interface and the a-Si:H/c-Si heterojunction interface. In the work presented here, a detailed analytical description is provided for the impact of both interfaces on the performance of such devices and especially on the device fill factor (FF). It has been found that the TCO work function can dramatically impact the FF by introducing a series resistance element in addition to limiting the forward biased current under illumination causing the well-known S-shape characteristic in the I-V curve of such devices. On the other hand, it is shown that the thermionic emission barrier at the heterojunction interface can play a major role in introducing an added series resistance factor due to the intrinsic a-Si:H buffer layer that is usually introduced to improve surface passivation. Theoretical explanation on the role of both interfaces on device operation based on 1D device simulation is experimentally verified. The I-V characteristics of fabricated devices were compared to the curves produced by simulation, and the observed degradation in the FF of fabricated devices was explained in light of analytical findings from simulation

The Effect of Annealing on the Structural and Optical Properties of Titanium Dioxide Films Deposited by Electron Beam Assisted PVD

Titanium dioxide thin films were deposited on crystalline silicon substrates by electron beam physical vapor deposition. The deposition was performed under vacuum ranging from 10−5 to 10−6 Torr without process gases, resulting in homogeneous TiO2-x layers with a thickness of around 100 nm. Samples were then annealed at high temperatures ranging from 500°C to 800°C for 4 hours under nitrogen, and their structural and optical properties along with their chemical structure were characterized before and after annealing. The chemical and structural characterization revealed a substoichiometric TiO2-x film with oxygen vacancies, voids, and an interface oxide layer. It was found from X-ray diffraction that the deposited films were amorphous and crystallization to anatase phase occurred for annealed samples and was more pronounced for annealing temperatures above 700°C. The refractive index obtained through spectroscopic ellipsometry ranged between 2.09 and 2.37 in the wavelength range, 900 nm to 400 nm for the as-deposited sample, and jumped to the range between 2.23 and 2.65 for samples annealed at 800°C. The minimum surface reflectance changed from around 0.6% for the as-deposited samples to 2.5% for the samples annealed at 800°C

Periodic inverse nanopyramid gratings for light management in silicon heterojunction devices and comparison with random pyramid texturing

status: Published onlin

Infrared Absorption Enhancement Using Periodic Inverse Nanopyramids in Crystalline-Silicon Bottom Cells for Application in Tandem Devices

Carefully tailored periodic nanostructures on the light wavelength scale, such as diffraction gratings, benefit from wave optics for efficiently trapping the weakly absorbing infrared photons in crystalline-silicon (c-Si) absorbers. In contrast with the conventional random pyramid texture, diffraction gratings can be designed to target specific wavelength ranges by the selection of the grating pitch. Absorption enhancement at infrared wavelengths in a silicon solar cell is especially desired when it operates below a perovskite top cell in a tandem device. In this article, inverse nanopyramid gratings of 800 nm pitch are proposed as an alternative front-surface texture to random pyramids in silicon heterojunction devices with interdigitated back contacts that are to be used as bottom cells in four-terminal perovskite/c-Si tandem devices. By doing so, we report a short-circuit current density gain of 0.53 mA/cm 2 with respect to the random pyramid texturing for the bottom c-Si cell. The rationale to substitute random pyramids by inverse nanopyramid gratings is, however, not justified in single-junction operation despite achieving the power conversion efficiency of 22.3% since the degraded optical performance at shorter wavelengths offsets the absorption enhancement at longer wavelengths, resulting in similar levels of short-circuit current densities for both texture types.status: Published onlin

Silicon Heterojunction Cells with Improved Spectral Response Using n-type mu c-Si from a Novel PECVD Approach

One of the promising ways to increase the efficiency of silicon heterojunction (SHJ) cells is to replace the doped hydrogenated amorphous silicon (a-Si:H) contact layer by doped hydrogenated microcrystalline silicon (mu c-Si:H) which has better suited opto-electrical properties. In this work, we report on the development of a plasma-enhanced chemical vapor deposition process for mu c-Si:H. We demonstrate an n-type mu c-Si:H layer with high crystalline fraction and low parasitic absorption. The developed layer is implemented as the front electron contact of a SHJ cell. A significant improvement in J(sc) of 0.9 mA/cm(2) is achieved on device level while maintaining high V-OC values (> 725 mV), leading to an efficiency of 20.6% for the best cell. Cell efficiency is limited by a decreased FF which is attributed to the increased sensitivity of mu c-Si:H layers to ITO sputtering damage.The authors gratefully acknowledge the financial support of imec's industrial affiliation program for Si-PV. Part of this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 657270