Abstract
In0.53Ga0.47As/GaAs-based quantum dot intermediate band solar cells (QDIBSCs) have been designed and optimized for the next generation photovoltaic technology. The wave behavior of charge carriers inside the dot and their barrier have been analyzed with different dot sizes and interdot spacing. The device characteristics such as short circuit current density, Jsc, open circuit voltage, Voc, and conversion efficiency, η, have been evaluated. Based on the behavior of electron wave function, it is found that varying the dot spacing leads to a change in the IB width and in the density of states, whereas varying the size of dots leads to a formation of a second IB. For a fixed dot spacing, two ranges of dot sizes vary the number of IBs in In0.53Ga0.47As/GaAs QDIBSC. Smaller dots of a size ranging from 2 nm to 5 nm form a single IB while larger dots of a size ranging from 6 nm to 9 nm can produce 2 IBs. The efficiency of 2 IBs close to 1 IB suggests that formation of multiple IBs can possibly enhance the device efficiency.
Highlights
The concept of an intermediate band solar cell (IBSC) has created enormous interests to replace the traditional solar devices
We demonstrated the influence of In0.53Ga0.47As/GaAs quantum dots (QDs) in the IBSC and obtained the values of horizontal and vertical dot spacing which exhibited the maximum efficiency [11]
We found the values of dot spacing which yielded the maximum efficiency for In0.53Ga0.47As/GaAs quantum dot intermediate band solar cells (QDIBSCs) [11]
Summary
The concept of an intermediate band solar cell (IBSC) has created enormous interests to replace the traditional solar devices. The intermediate band (IB) is attained by introducing an IB material between two selective contacts of p type and n type [3] which split the energy bandgap Eg into two subbandgaps. This allows the formation of additional electron–hole pairs from the absorption of two subbandgap energy photons [4]. The tight and regular arrangements of QDs in a quantum dot intermediate band solar cell (QDIBSC) lead to the formation of an IB or a superlattice miniband that is well separated in energy from the higher order states. The characteristic parameters of the device, such as conversion efficiency, η, short circuit current density, Jsc, and open circuit voltage, Voc, have been evaluated, and their relation with the widths and subbandgaps of the IB was derived
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