MSE302 - MSE 302 Solar Cell Characteristics Topics Jsc VOC...

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MSE 302 April 4, 2008 Solar Cell Characteristics Topics J sc , V OC , Fill Factor quantum efficiency parasitic resistance
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Definition of PV cell terms I SC = short circuit current V OC = open circuit voltage Fill factor = P max /I SC V OC
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A diode can be a photodetector, photovoltaic cell or an LED With negative I and V, the electric field is strong so carriers are efficiently separated. No power is generated. With positive V and negative I, electrons go to the higher potential electrode. Energy is collected. With positive V and I, carriers are injected. Energy is consumed. LED PV cell Photodetector In principle, the same diode can be used as an LED, PV cell or photodetector. To optimize the performance, however, different designs are needed.
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Efficiency definitions External quantum efficiency ( η e ). Also known as IPCE (incident photon to converted electron) efficiency Electron out/photons on the device Internal quantum efficiency ( η i ) = Electrons out/photons absorbed η i can be very high in a thin device because the electric field is high and the charge carriers don’t have far to go, but η e is low because not many photons are absorbed. Energy conversion efficiency = = electrical power generated incident optical power V oc I SC FF P in
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The quantum efficiency depends on the wavelength Note that the power conversion efficiency is much less than the quantum efficiency because all of the energy in each photon is not transferred into electrical energy.
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This note was uploaded on 12/01/2011 for the course MS&E 302 taught by Professor Mcghee during the Spring '08 term at Stanford.

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MSE302 - MSE 302 Solar Cell Characteristics Topics Jsc VOC...

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