Imaging solar cells using terahertz waves

Kayra, Seda
In this thesis, Terahertz Time-Domain spectroscopy (THz-TDS) was used in order to measure the electrical properties of silicon solar cells. The advantage of THz-TDS is that it allows us to measure the electrical properties without electrical contacts. In order to perform these measurements, a reflection based system was constructed and the changes in the peak amplitude in the time-domain under a, 450mW 808 nm continuous wave laser source were measured. The solar cell that was used in this thesis was manufactured in Middle East Technical University Microelectromechanical Systems (METU-MEMS) research laboratories located in Ankara, Turkey. The solar cell that we used in the measurements had a thickness of 0.45 mm and was produced on a single silicon crystal in <100> direction. It is made up of a p-type base and n-type emitter to create p-n junction. Also, it has a Si4N3 AR coating and Al back contacts on it. To compare the THz measurements to that of electrical measurements, some electrical contact measurements were performed on the solar cell under laser illumination. By using these measurements, the energy conversion efficiency and the quantum efficiency of the solar cell were calculated and measured as 3.44 % and 7%, respectively under the 450mW, 808nm illumination on a specific area of the cell. The results that were obtained form the electrical measurements were compared with the THz results. We found that in order to understand the efficiency of the solar cell using THz-TDRS, a more comprehensive study needs to be done where the changes in the reflection of the THz radiation under different excitation powers and different configurations of the system need to be studied.


Contact resistivity analysis of different passivation layers via transmission line method measurements
Kökbudak, Gamze; Turan, Raşit; Yerci, Selçuk; Department of Micro and Nanotechnology (2017)
Crystalline silicon (c-Si) homojunction solar cells constitute over 90% of the current photovoltaic market. Although the standard solar cells are cost effective and easy to process, their efficiency potential is unfortunately limited. Currently, more innovative cell concepts appeared with their high efficiency potential coupled with low costs. Since the recombination at surfaces and under metal contacts is one of the major obstacles against high conversion efficiencies, surface passivation has primary impor...
Development of hole transport transparent conductive electrodes for n-type crystalline silicon solar cells
Akdemir, Ozan; Bek, Alpan; İmer, Muhsine Bilge; Department of Micro and Nanotechnology (2018)
Conventional transparent conductive electrodes (TCEs) used in crystal silicon (c-Si) solar cells are commonly made of indium tin oxide (ITO) which provides low sheet resistance and high transparency. However, due to indium scarcity, ITO layers increase the fabrication cost; thus, alternative TCEs, such as fluorine-doped tin oxide (FTO), zinc oxide (ZnO), metal nanowires and Oxide/Metal/Oxide (OMO) multilayers, are being investigated. Conventional solar cells also make use of doped layers, to create the junc...
Surface modification of multi-crystalline silicon in photovoltaic cell by laser texturing
Radfar, Behrad; Turan, Raşit; Yerci, Selçuk; Department of Micro and Nanotechnology (2019)
Surface of crystalline silicon solar cell plays an important role in its performance. It affects the optical properties which can be determined by surface’ reflectance. To minimize the reflection from the flat surface, thus, improve light trapping, the crystalline silicon wafers must be textured. Through the texturing process, roughness is introduced at the surface, so the incident light has a larger probability of being absorbed into the solar cell. Monocrystalline silicon solar cells can typically be text...
Synthesis, electrochemical characterization and organic solar cell applications of selenophene containing conjugated polymers
Yaşa, Mustafa; Toppare, Levent Kamil; Department of Polymer Science and Technology (2017)
Donor-Acceptor (D-A) type conjugated polymers are very popular for potential applications such as organic light emitting diodes, solar cells, electrochromic devices and organic field effect transistors. In literature, cyclopentadithiophene and its derivatives are commonly used electron donor units for organic solar cells. The incorporation of selenium atom into polymer backbone results in low band gap polymers as compared to sulfur and oxygen counterparts. In this study, selenophene containing conjugated po...
Surface preparation passivation and patterning techniques used in silicon based heterojunction solar cells
Dönerçark, Ergi; Turan, Raşit; Department of Physics (2017)
For silicon Heterojunction (SHJ) solar cell technology features, a thin intrinsic hydrogenated amorphous silicon (i a-Si:H) layer has inserted between the crystalline silicon and doped amorphous silicon. The state of the art SHJ solar cell structure involves low temperature depositions of a-Si:H layer by means of Plasma Enhanced Chemical Vapor Deposition (PECVD) technique. Recent developments on SHJ solar cells have been focused on increasing the passivation quality of a-Si:H layer and the formation of all ...
Citation Formats
S. Kayra, “Imaging solar cells using terahertz waves,” M.S. - Master of Science, Middle East Technical University, 2011.