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

Abstract

Li doped NaYbF 4 :Ho 3+ -C 3 N 4 (UCNPs-C 3 N 4 ) nanocomposites were successfully prepared and applied in perovskite 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 NaYbF 4 :Ho 3+ (UCNPs) and 2D g-C 3 N 4 (C 3 N 4 ). 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-C 3 N 4 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-C 3 N 4 , 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 composites are not only beneficial to passivate the defects in the perovskite layer, but also improve the short-circuit current density ( J SC ) and photoconversion efficiency (PCE) of the device. Mechanism of NIR sunlight harvesting in the schematic diagram of PSCs • Upconversion nanoparticles (UCNPs) and two-dimensional graphitic carbon nitride (2D g-C 3 N 4 ) were successfully compounded. • UCNPs convert near-infrared light (NIR) into visible light (VIS). • 2D g-C 3 N 4 can reduce defect density of the perovskite layer. • The poor conductivity of UCNPs are increased by 2D g-C 3 N 4 . • The efficiency of device was optimized from 11.01% to 14.78% due to the synergistic effect of nanocomposites.