ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 1 ELEC3202- Coursework 1 Photovoltaics Characterization Laboratory For this coursework assignment, you are given results from a set of experiments performed to characterize photovoltaic materials and commercial solar cells with a measurement system that is used in university research groups and industrial R&D labs around the world. You should use this data to complete a series of tasks covering the analysis and discussion of the results. A video is available on the ELEC3202 Blackboard site that shows you the experimental setup and demonstrates how the results were collected. This assignment contributes 10% of the marks for ELEC3202 Submit your report via handin.ecs.soton.ac.uk by 4 pm on Friday 19th March 2021. ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 2 Aims, Learning Outcomes Having successfully completed this exercise, you will be able to: • Understand how to measure the quantum efficiency (QE) characteristics of solar cells. • Describe what limits QE in different parts of the spectrum • Analyse the reflectance spectra of silicon samples that have undergone various surface treatments to reduce reflectance. Outline Figure 1. Annotated photograph of the Bentham PVE300 Photovoltaics Characterisation System used to collect the data for this exercise. You will be provided with the following sets of measurement results collected using a Bentham PVE300 Photovoltaics Characterisation System1: SET 1: EQE and Reflectance spectra from a Back Surface Field (BSF) multicrystalline silicon solar cell. SET 2: Reflectance spectra from 7 sections of a monocrystalline silicon wafer, treated in different ways to reduce surface reflectance. You should use your results to complete the tasks in the “Analysis and Report Write-up” section presenting your work in an INDIVIDUAL report for electronic submission via handin.ecs.soton.ac.uk by 4 pm on Friday 19th March 2021. The report you submit will be marked and will contribute 10% of the total mark for ELEC3202. The mark scheme for this exercise is included later in this document. 1 https://www.bentham.co.uk/products/systems/pve300-photovoltaic-eqe-ipce-and-iqe-solution-16/ ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 3 Virtual Laboratory Session Please watch the video of the lab session provided on the ELEC3202 Blackboard website. The video, the notes below and the slides from the coursework lecture will guide you through how the quantum efficiency and reflectance measurements were taken. The results (SET 1 and SET 2) are available as Excel spreadsheets on the ELEC3202 Blackboard site. EQE Measurement The Bentham PVE 300 system used to collect the results consists of a white light source which is coupled through a monochromator and onto a solar cell (Figure 2). The wavelength of light incident on the cell is varied from 300 to 1100 nm in steps of 5 nm and the current produced by the cell is measured. This is first carried out on a solar cell with a known spectral response so that the incident power can be determined for each wavelength step. The procedure is then repeated for the solar cell under test. The spectral response is calculated and then converted to external quantum efficiency (EQE). Figure 2. Diagram showing the main components of the Bentham PVE for quantum efficiency measurement. Reflectance measure The Bentham PVE 300 system also features an integrating sphere for reflectance measurements (Figure 3). An integrating sphere is a hollow sphere coated on the inside with a diffuse white reflective material. A sample is placed at the rear port of the integrating sphere. Monochromatic light is directed onto the sample. Light reflected from the sample surface bounces around the inside of the integrating sphere, scattering at each encounter with the inner surface. This results in the inside surface of the sphere being uniformly illuminated by the light reflected from the sample. A photodetector is placed at another port in the sphere, the signal from which is proportional to the intensity of light reflected from the sample. To measure reflectance of a sample, (), monochromatic light is directed onto a reflectance standard of a known reflectance, (), at the rear of an integrating sphere. Current, (), from the detector is measured as the wavelength is swept. The reflectance standard is then replaced by the sample and the measurement is repeated to obtain (). Sample reflectance, (), is then determined using equation (1): () = ()�()() � (1) ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 4 Note that whilst it is possible to use the integrating sphere to measure transmittance, the cell measured for this lab has a metal contact over the entire back surface and so there is no transmission of light to account for in the determination of IQE. Figure 3. Diagram showing Bentham PVE300 system configured to measure reflectance. ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 5 Data Analysis You should work through the following tasks using the experimental data SET1 and SET 2 provided as Excel spreadsheets on the ELEC3202 Blackboard site. Task 1 (using SET 1) (a) Plot the external quantum efficiency (EQE) and reflectance spectra of the solar cell. (b) Calculate and plot the internal quantum efficiency (IQE) spectrum of the solar cell. (c) Describe what could be limiting the quantum efficiency of the cell in different parts of the spectrum. (d) From the data sheet given in the Appendix, calculate the typical power conversion efficiency of the type of solar cell tested in the lab (i.e. Back Surface Field (BSF) multicrystalline silicon solar cell). You can assume that the solar cell was measured under standard conditions, under an integrated solar irradiance of 1kW/m2. Show your working. (e) Review the literature to find an example of a crystalline silicon solar cell technology with a demonstrated power conversion efficiency higher than that of the cell measured for this lab. Write a one-page overview of its structure and operation, explaining how the design features lead to a high efficiency. Task 2 (using SET 2) (a) On a single graph, plot the reflectance vs. wavelength results for all the samples measured. (b) Using your knowledge of antireflective schemes for silicon, pair up the sample numbers with the descriptions in the table below. Give details of the method you used to determine which sample is which. For this exercise, you may assume the refractive index of SiO2 to be 1.46 and the refractive index of SiNx to be 2.0, independent of wavelength. Sample number Surface Bare Si (no coating) 40 nm SiNx 114 nm SiO2 131 nm SiO2 54 nm SiNx 87 nm SiNx Random pyramids + SLAR (c) From the untextured samples in the list, which one would you choose for a silicon solar cell and why? ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 6 Write-up and Submission Tasks 1 and 2 should be written up into a report with the following structure. A word document template is also provided. Title: ELEC3202- Coursework 1: Photovoltaics Characterization Laboratory 2021 Name: Username: Task 1 (a) (b) (c) (d) (e) Task 2 (a) (b) (c) The report should be no longer than 7 pages, including figures and references. You should expect to spend up to 10 hours on this assignment. For Task 1(e), you may wish to make use of other data sources and refer to the literature. Please make sure you properly reference any sources of information you use. You should submit an electronic copy of the report through handin.ecs.soton.ac.uk (link provided on Blackboard). The deadline for submission is 4 pm on 19th March 2021. Marks and feedback will be given after the Easter break. Late submissions will be penalised at 10% per working day. If you hand in more than 5 days late then no mark will be awarded. Please note the University regulations regarding academic integrity apply to this coursework assignment. ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 7 Assessment Criteria/Marking Scheme Task 1 (~5 hrs) 0 No evidence of task being attempted 9 Some graphs plotted correctly, some correct calculations but little description/ discussion/explanation 18 Some graphs plotted correctly, some correct calculations, some description/discussion/explanation or Full set of correctly plotted graphs and calculations, little description/discussion/explanation 26 Most graphs plotted correctly, most correct calculations, good description/discussion/explanation or Full set of correctly plotted graphs and calculations, some description/discussion/explanation 34 Full set of correctly plotted graphs and calculations, good description/discussion/explanation 42 Full set of correctly plotted graphs and calculations, excellent description/discussion/explanation 50 Full set of correctly plotted graphs and calculations, outstanding description/discussion/explanation Task 2 (~4 hrs) 0 No evidence of task being attempted 7 Some graphs plotted correctly, some correct calculations but little description/ discussion/explanation 14 Some graphs plotted correctly, some correct calculations, some description/discussion/explanation or Full set of correctly plotted graphs and calculations, little description/discussion/explanation 21 Most graphs plotted correctly, most correct calculations, good description/discussion/explanation or Full set of correctly plotted graphs and calculations, some description/discussion/explanation 28 Full set of correctly plotted graphs and calculations, good description/discussion/explanation 34 Full set of correctly plotted graphs and calculations, excellent description/discussion/explanation 40 Full set of correctly plotted graphs and calculations, outstanding description/discussion/explanation Writing, presentation and structure 0 No report 1 Poorly written, no figures or not understandable 3 Adequately written but with significant errors, unclear presentation of figures 6 Well written but with some errors in grammar and spelling, reasonably clear figures 8 Well written and structured, with only minor spelling or grammatical errors, well presented figures 9 Very well written and structured, hardly any errors, very well presented figures with clearly written captions 10 Extremely well written, structured and formatted, no spelling or grammatical errors, figures of a standard similar to published figures. TOTAL /100 (This will contribute 10% to your final mark for ELEC3202.) ELEC3202: Green Electronics Photovoltaics Characterization Laboratory 2021 8 Appendix: Data Sheet from manufacturers of solar cell tested in lab







































































































































































































































































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