Abstract
We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf's equations for the QE including a drift field E, and model E as being equal to the junction built-in voltage distributed uniformly across the depletion region.This allows us to calculate the QE as a function of L and depletion width WD. We show that if L is sufficiently small, increasing WD can actually decrease the QE. To determine how long L needs to be in a practical GaInNAs junction, we calculate from the QE the short-circuit current density as a function of WD and L. This allows us to estimate that Lambipolar needs to be greater than roughly 1 ?min order to obtain enough photocurrent for the 4-junction application, giving guidance to the experimental effort to develop such cells.
Original language | American English |
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Number of pages | 7 |
State | Published - 2005 |
Event | 31st IEEE Photovoltaics Specialists Conference and Exhibition - Lake Buena Vista, Florida Duration: 3 Jan 2005 → 7 Jan 2005 |
Conference
Conference | 31st IEEE Photovoltaics Specialists Conference and Exhibition |
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City | Lake Buena Vista, Florida |
Period | 3/01/05 → 7/01/05 |
NREL Publication Number
- NREL/CP-520-37418
Keywords
- depletion-region collection
- drift field
- photocurrent
- PV
- quantum efficiency (QE)
- solar cells