15 research outputs found
High aspect ratio triangular front contacts for solar cells fabricated by string-printing
No full textWe are presenting a novel method to fabricate high aspect ratio, triangular cross-section solar cell front contacts, henceforth referred to as string-printing. We optimized string-printing to yield contacts with an aspect ratio larger than 1 and a light redirection efficiency or effective transparency of 67%, thereby mitigating most of the optical losses inherent to flat metallic front grids. In string-printing, a string coated with silver paste approaches a substrate until contact is made. Withdrawing the string then leaves behind silver paste on the substrate. Here, we describe the fabrication method and show initial results including current density-voltage curves of string-printed silicon heterojunction solar cells, as well as the effective transparencies of the contacts. String-printing is a scalable, low-temperature process with high potential to boost commercial solar cell efficiency and lower the module price per Watt
CsPbCl₃:Yb³⁺ nanocrystals: Adverse effects of colloidally stable ytterbium-rich reaction by-products on luminescent down-conversion performance
No full textFew Photons Probe Third-Order Nonlinear Properties of Nanomaterials in a Plasmonic Nanocavity
No full textQuantification of nonlinear optical properties is important for nano-optical devices, yet such measurements remain challenging at the single-particle level. Here, enhanced optical fields are harnessed inside a plasmonic nanocavity to mediate efficient nonlinear interactions with an individual particle. Reflection Z-scan technique was performed on individual nanocavities, reaching down to two photons per pulse, thus demonstrating a significantly higher efficiency beyond conventional methods. The few photons are sufficient to extract the nonlinear refractive index and nonlinear absorption coefficient of different nanomaterials, including perovskite and Au nano-objects and a molecular monolayer. This work is of great interest for investigating nonlinear optical interactions on the nanoscale and characterizing nanomaterials, including fragile biomolecules.</p
Solvent-assisted Mechanochemical Synthesis of UV-absorbing, NIR-emitting CsPbCl3:Yb3+ Perovskite Powders for Spectral Conversion Applications
No full textCsPbCl3:Yb3+ nanocrystals: Adverse effects of colloidally stable ytterbium-rich reaction by-products on luminescent down-conversion performance
No full textThe development of near infra-red (NIR) emitting down-converters is a promising route for improving photovoltaic output through efficient light management. Quantum-cutting Yb3+-doped CsPbCl3 nanocrystals (NCs) are interesting for this application due to their high photoluminescence quantum yields (PLQY >100 %) and attractive NIR spectral properties which include high absorption cross section and minimal overlap between absorption and emission spectra. In this work, we fabricated CsPbCl3:Yb3+ NCs with the hot-injection method and studied them using structural/optical characterization methods such as x-ray diffraction, scanning transmission electron microscopy, energy-dispersive x-ray spectroscopy, fluorescence lifetime and quantum yield measurements. We found that the hot-injection method is susceptible to the formation of colloidally stable Yb-rich reaction by-products. After separating these by-products from the NCs, NIR PLQY increased by a relative 46 %. Although the PLQY values recorded in this study are 4–7 times lower than in other studies, these findings may explain some discrepancies in photoluminescence efficiency reported with this material
Few Photons Probe Third‐Order Nonlinear Properties of Nanomaterials in a Plasmonic Nanocavity
No full textQuantification of nonlinear optical properties is important for nano-optical devices, yet such measurements remain challenging at the single-particle level. Here, enhanced optical fields are harnessed inside a plasmonic nanocavity to mediate efficient nonlinear interactions with an individual particle. Reflection Z-scan technique was performed on individual nanocavities, reaching down to two photons per pulse, thus demonstrating a significantly higher efficiency beyond conventional methods. The few photons are sufficient to extract the nonlinear refractive index and nonlinear absorption coefficient of different nanomaterials, including perovskite and Au nano-objects and a molecular monolayer. This work is of great interest for investigating nonlinear optical interactions on the nanoscale and characterizing nanomaterials, including fragile biomolecules
