Before answering numerical exercises..REMEMBER THE FOLLOWING:
1) Pay attention to theunitsin which you have to introduce your answer. They are always given in the exercise formulation.
2) You don't have to insert the units or the "%" symbol in the answer box;just the number.
3) If you want to put decimals,use the periodsymbol".".
4) Some of the answers involvepowers of 10. For example, one exercise may ask you for the electron concentration in104cm−3. If your answer is, for example,4.5∗104cm−3, you will just need to insert in the answer box "4.5". If, on the other hand, your answer is4.5∗103cm−3, you will need to insert "0.45".
5)Lastly, if you want to be safe,do NOT round offyour answer unless explicitly stated. Too many decimals will never result in a wrong answer.
For this assignment, you may have to apply some of the useful constants and/or formulas provided here:
Download the Constants and Formulas
AQ4.1.1 MICROMORPH MODULE
(1 point possible)
Consider a small module based on interconnected tandem cells of hydrogenated amorphous and microcrystalline silicon as depicted in the figure below. TheVocof a single tandem cell is1.35Vand the short-circuit densityJscis12mA/cm2.
Which combination of the external parameters can reflect the external parameters of the module depicted in the figure above?
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a)Voc,module=16.2V,Isc,module=60mAb)Voc,module=16.2V,Isc,module=120mAc)Voc,module=32.4V,Isc,module=720Ad)Voc,module=32.4V,Isc,module=120mA
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AQ4.2.1 CIGS AND CDTE FABRICATION
During manufacturing of a CIGS device, the metal back contact is deposited first, while in case of the CdTe solar cells, the back contact is deposited in the last processing step. What are the configurations of both cells:
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Both the CI(G)S and CdTe solar cells are made in superstrate stucture.
The CI(G)S solar cell is made in a superstrate structure, whereas CdTe solar cell is made in a substrate structure.
The CI(G)S solar cell is made in a substrate structure, whereas CdTe solar cell is made in a superstrate structure.
Both CI(G)S and CdTe solar cells are made in substrate stucture.
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4.3.1 TRIPLE JUNCTION J-V CURVE
On the left-hand side of the figure below a III-V triple junction solar cell is shown. On the right-hand side, the J-V curves of the individual component cells and the multi-junction solar cell are shown.
Which junction corresponds to sub cell 3?
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Sub cell based on Ge.Sub cell based on GaAs.Sub cell based on GaInP.Sub cell based on GaInAs.
4.4.1 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
(1 point possible)
Solar simulators are used to study the performance of solar cells in the lab. In the figure below (left picture), the spectral power density of a solar simulator is shown with the blue line. The spectral power density of this solar simulator is given by:
P(λ)=7.5∗1015λ−2.25∗109[Wm−2m−1]for300nmλ<500nm
P(λ)=2.25∗109−1.5∗1015λ[Wm−2m−1]for500nmλ<1500nm
Where the wavelengthλis expressed in meters.
Calculate the irradiationIof the solar simulator (inWm−2)
The area under the curve (i.e. the integral of P with respect to lambda) gives the irradiance: 900 W/m2
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4.4.2 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
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What is the photon flux of the solar simulator (in1021m−2s−1)?
Taking the peak wavelength for conversion gives
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4.4.3 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
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The EQE of a tandem cell with junction A and junction B under short-circuited (V = 0 V) condition is also presented in the previous figure (right picture).
Which junction acts like the top cell in the tandem cell?Top of Form
A
B
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4.4.4 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
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What is the band gap (in eV) of the absorber layer of the junction A?
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4.4.5 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
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Calculate the short-circuit current densityJscof junction A (inmA/cm2) if the solar cell is measured under the solar simulator.
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4.4.6 EXTERNAL QUANTUM EFFICIENCY OF A TANDEM CELL
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Junction B has a different absorber layer than junction A. Above its band gap, the solar cell B has an EQE = 0.60 that remains constant. Calculate the short-circuit current densityJscof the junction B (inmA/cm2) if the solar cell is measured under the solar simulator.
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AQ4.5.1 DYE-SENSITIZED SOLAR CELL
(1 point possible)
Consider an organic solar cell consisting of aTiO2semiconductor with an ionization energy of7.8eVand a polymer with an electron affinity of3.4eV. Which of the following band diagrams corresponds to the organic solar cell? The band gap ofTiO2is3.5eV.
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(a)
(b)
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AQ4.5.2 DYE-SENSITIZED SOLAR CELL
(1 point possible)
What is the driving force (in eV) for electron injection from the polymer to the semiconductor?
0.9 eV
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AQ4.5.3 DYE-SENSITIZED SOLAR CELL
(1 point possible)
The electron diffusion coefficient isDe=4∗10−5cm2/sand the thickness ofTiO2is4μm. What is the lifetime of the injected electrons (inms)?
4 ms
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b) Voc,module=16.2V, Isc,module=120Ma
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