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(a) and (b) Simulated equilibrium band diagrams of the QJ and the field-enhanced QJ structures, respectively. (c) and (d) Simulated band diagrams at open circuit conditions for the same structures as in (a) and (b), respectively, under 1000 W/m solar illumination. The field-enhanced QJ exhibits a higher open circuit voltage due to the increased separation between the Fermi levels of the p-type and N-type layers and (e) a higher built-in voltage at the equilibrium. (f) Simulated electric field inside the solar cell active layers at the maximum power point. The field-enhanced QJ architecture exhibits a higher electric field magnitude. The electric field vector is directed towards the p-layer, driving minority holes towards their respective contact during photovoltaic operation.
Comparison between experiments and simulations for (a) open circuit voltage, (b) short circuit current, (c) fill factor, and (d) power conversion efficiency as a function of the electronic bandgap of the top N layer. The smallest bandgap point is equivalent to the quantum junction device.
(a) Current-voltage characteristic of a typical QJ device and the best field-enhanced QJ device. (b) Comparison of device figures of merit for the QJ and optimized field-enhanced QJ structures.
Simulated Voc (a) and PCE (b) as a function of the donor density in the N layer for a field-enhanced QJ.
Mean value of PCE and statistical error evaluated on 20 best QJ and field-enhanced QJ devices.
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