Theoretical study of the efficiency of strained core/shell quantum dot solar cells

Under the effective mass approximation and dielectric continuum model, based on the detailed balance model, the photoelectric conversion efficiency, open circuit voltage and short circuit current density of zinc-blende and wurtzite strained quantum dot solar cell are studied. The results show that the efficiency of photoelectric conversion and the open-circuit voltage decrease as the core size of quantum dot increases, while the short-circuit current density increases. Because the strain increases the quantum dot band gap, the short-circuit current density decreases, however both the photovoltaic conversion efficiency and open-circuit voltage increase. Furthermore, the process of multiple exciton generation can considerably enhance the conversion efficiency of solar cells. By comparing the two structures, it is found that the photoelectric conversion efficiency and open circuit voltage in the wurtzite structure are higher than that in the zinc-blende structure, while the short circuit current density is lower than that in the zinc-blende structure.