Abstract
This work aims to evaluate quantum-dot intermediate-band solar cells (QDIBSCs) from two points of view. The first focuses on study of the dynamic characteristics of a model built on investigation of the effect of optical generation and recombination lifetimes on the induced electron density, induced photocurrent, and thus power conversion efficiency. In this phase, the main factors affecting emission and absorption of charge carriers are discussed, being found to depend on QDIBSC parameters such as the quantum dot (QD) size, barrier width, and doping density in the intrinsic region. Also, the solar wavelength response is determined. The relations between the photocurrent, efficiency, and model parameters such as the recombination lifetime and incident solar wavelengths are studied. The maximum values of photocurrent and efficiency obtained are 350 mA/cm
2
and 76%, respectively. The second part is devoted to determination of the allowable number of intermediate bands (IBs) for a certain material composition (InAs
0.9
N
0.1
/GaAs
0.98
Sb
0.02
), representing a research derivation. The bandgap and subbandgap energies, and corresponding response wavelengths are determined. Their optimum values to achieve the maximum efficiency (about 74% at maximum solar concentration) are given. The main contribution distinguishing this work is the ability to apply the general condition for the QD intrinsic region to the research derivation. This opens the way to experimental achievement of the different types of IBs in order to obtain the required efficiency.