Enhance the photoconversion efficiency of carbon-based perovskite solar cells through the synergetic effect of upconversion nanoparticles Li doped NaYbF4:Ho3+ and 2D g-C3N4

Li doped NaYbF4:Ho3+-C3N4 (UCNPs-C3N4) nanocomposites were successfully prepared and applied in perov-skite solar cells (PSCs). The photoelectric conversion efficiency of the modified PSCs can be increased from 11.01% to 14.78%. The improved efficiency can be attributed to the synergistic effect of Li doped NaYbF4:Ho3+ (UCNPs) and 2D g-C3N4 (C3N4). On the one hand, UCNPs can continuously absorb two or more low-energy photons and emit one high-energy photon, which allows UCNPs to improve the ability of perovskite layers to capture near-infrared light and convert it into visible light. The perovskite photosensitive layers will further absorb the converted visible light energy, and generate additional photocurrent. On the other hand, g-C3N4 exhibits high electrical conductivity and reduces its intrinsic defect density by effectively passivating the grain boundaries of the charge recombination centers. By performing hydrothermal loading experiments on UCNPs and g-C3N4, the defect of poor electrical conductivity of UCNPs can be significantly improved. The prepared composite material has higher absorption and utilization rate of sunlight. In conclusion, the synthesized com-posites are not only beneficial to passivate the defects in the perovskite layer, but also improve the short-circuit current density (JSC) and photoconversion efficiency (PCE) of the device.

Automated summary

Li-doped NaYbF4:Ho3+-C3N4 (UCNPs-C3N4) nanocomposites were successfully prepared and applied in perovskite solar cells, leading to an improved photoelectric conversion efficiency from 11.01% to 14.78%. The synergistic effect of UCNPs and C3N4 contributed to the enhancement of efficiency.