Designing energetic landscape in the multi-bandgap lead sulphide colloidal quantum dots ensemble for efficient solar spectrum utilization

Abstract

The distinctive nature of the solar spectrum in the near and shortwave infrared region demands the appropriate design of the active materials for efficient infrared photon absorption in a solar cell. Colloidal quantum dots (CQDs) based on lead sulphide (PbS) showed significant absorption in the near and shortwave infrared region through bandgap tuning. Despite their high absorption coefficient, PbS CQDs show a strong excitonic absorption peak, which cannot cover a significant portion of the solar spectrum in the near or shortwave infrared region. Mixing CQDs with different bandgaps can lead to better coverage of the solar spectrum and, hence, better photon absorption. In this work, we have estimated the ideal PbS CQD-based multi-bandgap ensemble combination and active material design strategy for optimum infrared photon absorption. In addition, we have investigated in detail the crucial factors that decide the performance of solar cells based on multi-bandgap CQDs. The simulation shows that careful optimization of the energetic landscape of the ensemble, along with the charge carrier mobility, can improve the efficiency up to 16.48 % under the AM 1.5 G spectrum. The optimized infrared photovoltaic performance with a perovskite filter can reach up to 9.29 %.