Investigation of hybrid Ge QDs/Si nanowires solar cell with improvement in cell efficiency

In this paper, the structure of a high-efficiency solar cell is presented by using a combination of quantum dots of germanium arrays and silicon nanowires on a thin film silicon layer. Due to the low absorption coefficient of silicon, this type of solar cell does not have high efficiency. According to the capability of the quantum structure in absorbing the incident photons and the generation of electron-hole pairs, this structure is proposed. Moreover, nanowires as an appropriate suggestion are applied in our work aiming to improve light scattering and optical photon absorption for the generation of carriers. Both of the electrical and optical characteristics of the solar cell are calculated by using a finite-difference time-domain method. Owing to the change of the nanowire length and increasing the number of quantum dot in our work, maximum power absorption is achieved. The achieved results provide a considerable improvement in efficiency and short-circuit current density. The efficiency is improved up to 17.5% and the short-circuit current density in the active layer of thickness 1170 nm has been provided to be 42.6 mA/cm(2). The open circuit voltage for this cell is calculated to be 0.47 V. The achieved results provide a considerable improvement in efficiency and short-circuit current density in comparison with previously published method.