Lithium-Based Upconversion Nanoparticles for High Performance Perovskite Solar Cells

Abstract

In this work, we report an easy, efficient method to synthesize high quality lithium-based upconversion nanoparticles (UCNPs) which combine two promising materials (UCNPs and lithium ions) known to enhance the photovoltaic performance of perovskite solar cells (PSCs). Incorporating the synthesized YLiF4:Yb,Er nanoparticles into the mesoporous layer of the PSCs cells, at a certain doping level, demonstrated a higher power conversion efficiency (PCE) of 19%, additional photocurrent, and a better fill factor (FF) of 82% in comparison to undoped PSCs (PCE = ~16.5%; FF = 71%). The reported results open a new avenue toward efficient PSCs for renewable energy applications.

Efficient Lithium-Based Upconversion Nanoparticles for Single-Particle Imaging and Temperature Sensing

“…To explore the water solubility of the synthesized oleate-capped particles without losing their good optical properties, a surface–ligand exchange experiment was carried out. For this, the synthesized oleate-capped UCNPs were dispersed in acidic ethanol with a pH equal to 1 under strong sonication for one hour and collected after appropriate washing steps [ 19 , 22 ]. Details on this surface–ligand exchange method can be found in Materials and Methods.…”

“…The synthesized oleate-capped LiYF4:Yb,Er UCNPs (1.0 mL) were dispersed in a volume of 30 mL of acidic ethanol solution (pH = 1). The acidity of the ethanol solution was adjusted by concentrated hydrochloric acid [ 22 ]. A strong sonication was applied to the solution for 1 h to remove the oleate ligands and allow hydroxide ligand formation on the UCNPs’ surface.…”

Electrodeposition of Lithium-Based Upconversion Nanoparticle Thin Films for Efficient Perovskite Solar Cells

“…Under a green excitation at an intensity of 20 W•cm −2 , the perovskite film in the UC-PSC device showed a strong emission peak at 780 nm, higher than that of the pristine film, as shown in Figure 3a. This observation could be attributed to the following explanations: first, that the grain boundaries were reduced by the electrodeposited UC thin films [27], second, that the non-radiative recombination was suppressed, and third, that the defect trap states were minimized [10,27]. Proceeding, we experimentally performed photocurrent density-voltage curves (J-V) under 1-sun illumination at AM 1.5 G to test the photovoltaic performance of the fabricated PSC devices.…”

“…Their ability to upconvert one or more low-energy NIR photons to one high-energy visible photon, as well as their photostability and photoluminescence tunability, opens the door for advanced and promising applications [1][2][3][4][5]. These include bio-applications, quantum sensing, optoelectronics, superresolution microscopy, and renewable energy [6][7][8][9][10][11][12][13][14][15].…”

“…As the perovskite solar cells are considered to be the best alternative to the silicon-based solar cells, thin UC film technology applications in PSCs remains unexplored in detail. UCNP thin films are expected to enhance perovskite solar cells' (PSCs) power conversion efficiency due to their exceptional near-infrared light (NIR) responsivity [10][11][12][13]. In addition, the UCNP thin films in PSCs will work as a spectral converter to harvest the near-infrared (NIR) solar photons from sunlight and convert them to absorbable visible light photons by the perovskite light-harvesting active layer [10,11].…”