Browsing by Author "Lay, T. S."

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Numerical Study of Quantum-Dot-Embedded Solar Cells
(2013-09-01)
Lin, Chien-Chung
;
Tan, Ming-Hsuan
;
Tsai, Che-Pin
;
Chuang, Kuei-Ya
;
Lay, T. S.
A quantum-dot-embedded solar cell model with antireflection coating is proposed and studied numerically. The device model was designed by using MATLAB coding. A proper inclusion of quantum-dot-enhanced carrier absorption was achieved through a modified absorption coefficient and a structure dependent carrier lifetime. The transmission matrix and quasi-drift diffusion method were applied to simulate the optical and electrical characteristics of the device. The experimental results were fitted first to validate the model and provide parameters for optimization. The final simulation showed that the power conversion efficiency (PCE) of an ideal InGaP/GaAs+InAs QD dual-junction cell could achieve 39.04%.
Photovoltaic response for high density InGaAs coupled quantum dots
(2012)
Chuang, K. Y.
;
Tzeng, K. D.
;
Tzeng, T. E.
;
Lay, T. S.
;
Lin, Chien-chung
In order to enhance absorption at infrared range for GaAs based solar cell, we insert the nine-layer of vertically coupled quantum dots (VCQDs) into the active layer. We fine modulated the GaAs spacer thickness of coupled In0.75Ga0.25As QDs, and investigated the effects on photovoltaic response. For the open-circuit voltage (V-oc), the values decreases from 0.61 V to 0.55 V as the spacer thickness (d) decreases from d=15 nm to 5 nm for the nine-layer VCQDs solar cells. The reduction of V-oc for the VCQDs solar cells is attributed to the accumulation of compressive strain energy in the active QD region. For the sample of d=10 nm shows the best performance of current density (J(sc)similar to 24 mA/cm(2)) and efficiency (eta similar to 10.6). The J(sc) and eta, are increases by 55% and 112% more than the device without QDs, respectively.