risk assessment report
Ahmed_Jumaan
SkiteTechnologies.pptxPerovskite Rainbow Solar Cells
Ahmed Al Jamaan, Madeleine Tang Adams, Truc Thanh Tran, Manasi Vyas
Test materials when we get them to ensure purity and high performance, emitting in the right wavelength after absorbing. Then, once they’re in the solar cell, characterize the whole unit. In solar cell - scanning tunnelling electron microscope. Light absorbance and reflectance from particles.
Application Description
Our company is committed to developing a new type of solar cell using perovskite thin film technology, supplemented with varying sizes of quantum dots to enhance the harvesting of light from a wider variety of spectra, ultimately creating an efficient rainbow solar cell.
Solar Cells: Description and Current Applications
Description:
Solid structure technology that converts solar radiation into electrical energy
Also called photovoltaic cells
Supplies direct current (DC) through the cell as the battery
The voltage supplied by the cells alternate with any change in resistance
Applications include:
Generating electrical power from sunlight through solar panels
Solar lighting
Charging solar car batteries through car roof panels
Heating and cooling
Perovskite
Displays a variety of properties including superconductivity and magnetoresistance, and being easily synthesizable
Solar cell applications include a perovskite structured compound
Hybrid organic-inorganic lead or tin halide-based material as the light-harvesting active layer
Pros:
Ease of fabrication
Strong solar absorption
Low non-radiative carrier recombination rates
Madeleine
Perovskite Cont.
Tin Perovskite vs Lead Perovskite
Tin Perovskite (CH3NH3SnI3): low toxicity, ideal choice of band gap
Lead Perovskite (CH3NH3PbX3): high toxicity, greater stability when exposed to oxygen
Solution: A mixture of Sn and Pb Perovskite
Quantum Dots
Tiny particles or nanocrystals of a semiconducting material with diameters in the range of 2-10 nm
They absorb photons and re-emit the photons at different wavelengths
Absorption and remission are directly related to size
Manasi
Quantum Dots Cont.
Quantum Dots can be classified between different types based on their composition and structure
Selecting the size and materials of our QDs allows us to tune the bandgap throughout most of the solar spectrum
Quantum Dots Cont.
Options: SnS, PbS, CdSe → all have different band gaps
SnS, PbS: narrow band gap, optically active in the infrared and near infrared region
CdSe: a wide variety of applications, large surface area to volume ratio, efficient light absorber
→ Our selection: CdSe
Rainbow Solar Cell
Idea: Use different sized quantum dots to harvest a larger section of the sunlight spectrum
Each quantum dot is tuned to a specific wavelength of light to enhance light absorption
Characterizing Rainbow Cells
Two main challenges to achieve maximum efficiency (greater than 30%):
Organizing the light harvesting nanostructures
Quantum dots should generate multiple charge carriers to be captured to generate photocurrent.
Solution:
Experiments in nanostructure and different-sized quantum dots assembled in an orderly fashion
Rainbow Cells Details
Four different sizes of quantum dots exhibited absorbent peaks at different wavelengths
3-nm quantum dots offered the best compromise: faster rate of electron convert and greater absorbance.
Rainbow Cell Architecture
Small QDs on the outer edge of the cell absorbing blue light, larger QDs located in the inner layer absorbing red light
Nano architectures: Particle films and nanotubes experiments
Hollow 8000-nm-long nanotubes (both the inner and outer surfaces are accessible to quantum dots)→ more efficient electron transport than films
Schematic Diagram Illustrating Energy Level of Different-sized CdSe Quantum Dots and TiO2
Rainbow Cell Architecture (cont’d)
Materials: anchoring CdSe quantum dots on TiO2 nanotubes to create an ordered assembly of nanostructures
Rainbow Cell Summary
Faster electron injection rate of small quantum dots and greater absorption range of larger quantum dots → higher efficiency
Absorb more wavelengths of light from the visible to the infrared region of the solar spectrum
Current and Future Applications: Is a Nanotechnology Application Superior?
Current Application: Silicon Solar Cells
Most popular solar cells
Good efficiency (15-20%)
Relatively more expensive to make
Only absorbs in the red to near-infrared portion of the light spectrum
Future application: Perovskite Rainbow Solar Cells enhanced with QDs
Potential for high efficiency (greater than 30%)
Strong structure
Low-cost scalable solar cells to make.
Lighter weight for easy transportation
Has the potential to absorb a broader range in the light spectrum
Ahmed
Graph Takeaways:
A gap in efficiency is present between theory and application
Goal: maintain the efficiency of PV solar cells while enlarging its surface area and using it in conditions subject to changes in weather → gap present between theory and application
Perovskite is rapidly growing in efficiency
Thousands of chemical compositions to experiment with to determine max efficiency
Major Limitations to Overcome
Lack of stability
Lack of research
Electrode materials cheaper than gold have a short lifespan
Deterioration occurs rapidly in the presence of moisture
Heavy encapsulation for protection can add to cost and weight
Scaling up
Toxicity
PbI is one of the breakdown products of perovskite
Substance is known to be toxic
May be carcinogenic (although this is still an unproven point)
Cd also has toxic properties
Encase in acrylic or gas (counter to second bullet)
Scaling up - reported high efficiency ratings have been achieved using cells too small to be used in an actual solar panel
Researchers are constantly seeking substitutions, and have already made working cells using tin instead with 6% efficiency that is improving.
Characterization and Manufacturing
Characterization will be performed on the materials and final product
Test materials need to be characterized the moment we get them to ensure purity and high performance
Materials need to be emitting in the right wavelength after absorbing photons
Once the solar cell is built, the unit needs to be characterized for light absorbance and reflectance from particles
Types of characterization for primary particles and final product:
Size distribution
Shape
Surface chemistry
Surface area
Absorption
Manasi/Truc
Characterizing nanomaterials
Scanning Tunnelling Electron Microscope:
Shows 3D image of a surface on an atomic level
Displays the distribution of particles in our final products
Measures conductivity of nanomaterial using an atomically sharp needle 1 nm away from the surface of a substrate and applying a voltage in between → Allows us to measure the charge conductance of our nanomaterials
Atomic Force Microscopy
Designed to measure local properties including friction, magnetism, surface chemistry, and shape of particles
Allows us to detect irregularly shaped nanoparticles, which can reduce the efficiency of a solar cell
Test materials when we get them to ensure purity and high performance, emitting in the right wavelength after absorbing. Then, once they’re in the solar cell, characterize the whole unit. In solar cell - scanning tunnelling electron microscope. Light absorbance and reflectance from particles.
Characterizing Nanomaterials Cont.
Dynamic Light Scattering: Measures nanoparticle size
Particles undergo Brownian motion in solution → DLS monitors this phenomena by light scattering. The size of the particle is extracted from this information
Allows us to determine the size of our nanocrystals to see how that impacts absorption
Z-Scan: Measures nonlinear absorption and nonlinear refraction
A sample is translated through the beam waist of a focused beam and the power transmitted through the sample is measured
Allows us to create an absorption spectrum for our QDs and to thus measure their efficiency
Top down or bottom up?
Bottom-up manufacturing - Quantum dots
CdSe QDs are produced by injecting cadmium and selenium precursor solutions into a heated growth solution, which form CdSe clusters that become continually growing QDs as the reaction progresses
Synthesis involves selective growth on patterned surfaces
A vapor-phase method will be used by growing layers in an atom-by-atom process
Self-assembly of nanostructures in material will be grown by molecular beam epitaxy
Enables selective growth on patterned surfaces
Madeleine
RESOURCES:
Bawendi Group. (n.d). Massachusetts Institution of Technology. Introduction and Theory. Retrieved from: http://nanocluster.mit.edu/research.php#Synthesis_and_characterization
Cornell, C. (2016). Perovskite Solar Cell: Key To A Brighter Solar Future? Retrieved from: https://www.huffingtonpost.com/clayton-b-cornell/perovskite-solar-cell-key_b_11069628.html
Cha, Mingyang, et al. "Enhancing Perovskite Solar Cell Performance by Interface Engineering Using CH3NH3PbBr0.9I2.1 Quantum Dots." Journal of the American Chemical Society, vol. 138, no. 27, 26 June 2016, p. 8581–8587. Journal of the American Chemical Society, pubs.acs.org/doi/abs/10.1021/jacs.6b04519.
Han, J, et al. “Enhancing the Performance of Perovskite Solar Cells by Hybridizing SnS Quantum Dots with CH3 NH3 PbI3.” Small, vol. 13, July 10th, 2017. https://doi.org/10.1002/smll.201700953
Highly Oriented Low-Dimensional Tin Halide Perovskites with Enhanced Stability and Photovoltaic Performance. Yuqin Liao, Hefei Liu, Wenjia Zhou, Dongwen Yang, Yuequn Shang, Zhifang Shi, Binghan Li, Xianyuan Jiang, Lijun Zhang, Li Na Quan, Rafael Quintero-Bermudez, Brandon R. Sutherland, Qixi Mi, Edward H. Sargent, and Zhijun Ning. Journal of the American Chemical Society 2017 139 (19), 6693-6699 DOI: 10.1021/jacs.7b01815
J. Mater. A critical review on tin halide perovskite solar cells. Chem. A, 2017,5, 11518-11549
Kongkanand, Anusorn, et al. “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture.” ACS Publications, Journal of the American Chemical Society, 1 Mar. 2008, pubs.acs.org/doi/full/10.1021/ja0782706.
Matthew L. Landry, Thomas E. Morrell, Theodora K. Karagounis, Chih-Hao Hsia, and Chia-Ying Wang. (2014). Simple Syntheses of CdSe Quantum Dots. Journal of Chemical Education 91 (2), 274-279. DOI: 10.1021/ed300568e
Nanowerk. (n.d.). Retrieved October 17, 2017, from https://www.nanowerk.com/spotlight/spotid=45249.php
Valizadeh, Alireza, et al. "Quantum dots: synthesis, bioapplications, and toxicity." Nanoscale Research Letters, vol. 7, no. 1, 28 Aug. 2012, p. 480. National Center for Biotechnology Information, doi:10.1186/1556-276X-7-480.
Winter, M. (n.d.). Silicon: the essentials. Retrieved October 17, 2017, from https://www.webelements.com/silicon/
Zyga, Lisa. "Quantum Dots May Lead to Rainbow Solar Cell." 7 Mar. 2008, phys.org/news/2008-03-quantum-dots-rainbow-solar-cell.html.
