Achieving over 50% efficiency in truncated conical QD-IBSCs through parameter optimization

Quantum dot intermediate band solar cells (QD-IBSCs) have attracted significant attention as a promising approach to enhance solar cell efficiency by two-step two-photon absorption. The Shockley-Queisser limitation has been resolved by using QD-IBSCs, which was a challenge for solar cell commercialization. In this study, we employed an efficient approach in QD-IBSCs to enhance the solar cell efficiency by using the truncated conical quantum dot (TCQD) shape. The effect on the performance of TCQD-IBSC has been symmetrically examined by varying the geometrical parameters, band gap, electron affinity, doping concentration, absorber layer thickness, and carrier mobility. Interestingly, TCQD-IBSC showed an efficiency of 51.1%, which decreases to 12.3%, 14.1%, and 26% with the increase in bandgap, doping concentration, and electron affinity, respectively. Notably, we improved the short-circuit current density by increasing the thickness of the absorber layer to 330 nm and carrier mobility to 4000 cm²V⁻¹s⁻¹, which led to higher power conversion efficiencies (PCE) of the solar cell. Moreover, a trade-off relation has been observed between QD size and interdot spacing. The PCE is gradually decreased from 49 % to 41.4 % with the increase in temperature. This model structure provides a new direction toward the achievement of high-efficiency TCQD-IBSCs and may promote the development of next-generation solar cells with high efficiency.