Photon Etc (Canada)

Abstract A multipurpose interconnection layer based on poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), and d‐sorbitol for monolithic perovskite/silicon tandem solar cells is introduced. The interconnection of independently processed silicon and perovskite subcells is a simple add‐on lamination step, alleviating common fabrication complexities of tandem devices. It is demonstrated experimentally and theoretically that PEDOT:PSS is an ideal building block for manipulating the mechanical and electrical functionality of the charge recombination layer by controlling the microstructure on the nano‐ and mesoscale. It is elucidated that the optimal functionality of the recombination layer relies on a gradient in the d‐sorbitol dopant distribution that modulates the orientation of PEDOT across the PEDOT:PSS film. Using this modified PEDOT:PSS composite, a monolithic two‐terminal perovskite/silicon tandem solar cell with a steady‐state efficiency of 21.0%, a fill factor of 80.4%, and negligible open circuit voltage losses compared to single‐junction devices is shown. The versatility of this approach is further validated by presenting a laminated two‐terminal monolithic perovskite/organic tandem solar cell with 11.7% power conversion efficiency. It is envisioned that this lamination concept can be applied for the pairing of multiple photovoltaic and other thin film technologies, creating a universal platform that facilitates mass production of tandem devices with high efficiency.

The Outlook article 'Combinations on trial' (Nature 552, S67-S69; 2017) overstated the number of immunotherapeutic agents in development at more than 2,400.In fact, there are roughly 2,000.

The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species’ fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, and single-molecule resolution in vivo.

Detection of sulfur by optical emission spectroscopy generally presents some difficulties because the strongest lines are in the vacuum UV below 185 nm and therefore are readily absorbed by oxygen molecules in air. A novel concept for a low-cost and efficient system to detect sulfur using near-IR bands by laser-induced breakdown spectroscopy is here proposed. This concept is based on customized thick holographic gratings as spectral filtering elements. The signal integration and the temporal synchronization are performed using built-in custom electronics that amplify and integrate or trigger photodiode output signals. In this work, we use the near-IR lines at 921.287 nm and a background reference at 900 nm. Preliminary results show a limit of detection comparable to that of a conventional high-end system.

A reflectometric singlemode elliptical-core fibre strain sensor is described. The sensor is based on optical frequency-modulated continuous-wave interference and can be used to measure remotely the strain variation of a distant large construction. The advantages of the sensor include high resolution, long dynamic range, long gauge length, and good stability.

We discuss the possibility of improving the optical efficiency of ELT instruments by reducing the number of optical surfaces with highly aspheric optics generated by deformable mirrors (DMs). Preliminary analysis shows that a 2 aspheric mirror design could in principle replace a traditional optical design with a complex series of ~ 10 lenses, providing a potential gain in efficiency of ~ 20% as well as a significant gain in compactness. New OH suppression systems based on technologies from the photonics world become available that may ultimately allow to reduce the near IR sky brightness by 2 to 4 magnitudes, depending on wavelength. The potential performance of an ELT with OH suppression is similar in imaging and significantly higher in spectroscopy than JWST.

An all-fiber single-mode fiber unbalanced Sagnac gyroscope is described. The gyroscope is based on optical frequency-modulated continuous-wave interference and consists primarily of four Y-type single-mode fiber directional couplers and a single-mode fiber coil. The rotational velocity of the fiber coil is determined simultaneously by detection of the phase shift of the beat signal. The advantages and limitations of the gyroscope are discussed.

This paper introduces a coherence hypothesis, which is modified from the classical coherence theory and can explain the effect of the spectrum bandwidth of light source on the signal of optical frequency-modulated continuous-wave (FMCW) interference.

A singlemode fibre frequency-modulated continuous-wave Sagnac gyroscope is described. The rotation speed of the fibre coil can be determined simultaneously by detecting the phase shift of the beat signal produced by two counter-propagating laser beams in a singlemode fibre coil. A resolution of 0.02°/s with a 100 m fibre coil has been observed.