Ultrathin films of highly monodispersed luminescent Si nanoparticles are directly integrated on polycrystalline Si solar cells. The authors monitor the open-circuit voltage and the short circuit current. The results demonstrate that films of 1nm blue luminescent or 2.85nm red luminescent Si nanoparticles produce large voltage enhancements with improved power performance of 60% in the UV/blue range. In the visible, the enhancements are ∼10% for the red and ∼3% for the blue particles. The results point to a significant role for charge resonant transport across the nanofilm and Schottky-like rectification at nanoparticle-metal interface.

Charges as small as 1 pC degrade the performance of high precision inertial reference instruments when accumulated on their test masses (TM). Non-contact charge management systems are required for the most sensitive of these instruments, with the TM charges compensated by photoelectrons in a feedback loop with a TM charge measurement system. Three missions have successfully demonstrated this technique: GP-B, the LISA Pathfinder, and the UV-LED mission, launched in 2004, 2015, and 2014 respectively; with the first two using the 254 nm Hg line and the last one a set of 255 nm UV-LEDs. UV-LEDs represent a significant improvement over the discharge sources, in terms of reliability, lifetime, switching speeds, power consumption, weight, and volume. Charge management techniques that eliminate the charge measurement and feedback systems, referred henceforth as passive, reduce the complexities and disturbance effects introduced by these systems, and are thus the subject of active research and development work. Passive charge management depends critically on the stability and reproducibility of the photoemission properties of a given system. In support of this work, we present comprehensive flight characterization data for a suite of 16 UV-LEDs in various configurations and 255 ± 1 nm center wavelength. We back up our results with ground-based measurements performed in configurations comparable to the flight one between September 4, 2020, and October 8, 2020. Results confirm the reliability of the UV LEDs in space environment and are fully consistent with the findings of ground studies. We find that the equilibrium potential of the TM, under illumination by the 255 nm LEDs, is independent of the UV intensity and reproduceable to about ± 6 mV, or ± 6 fC/pF, over periods of up to six months. The value of the equilibrium potential is dependent on the geometry of the electric field between TM and enclosure.

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The mini Space Time Asymmetry Research (mSTAR) is a proposed space mission to perform an advanced Kennedy-Thorndike (KT) test of Special Relativity using the large and rapid velocity modulation available in low Earth orbit (LEO). The mission goal is to test special relativity by performing a clock-clock comparison experiment in LEO, thereby testing the boost dependence of the speed of light. Clocks with stabilities better than 10 15 level at orbit time will allow the KT coefficient to be measured with up to two orders of magnitude higher accuracy than current ground-based experiments, with an additional factor of 10 possible using more advanced technology. In the current baseline, mSTAR utilizes an absolute frequency reference based on modulation transfer spectroscopy of molecular iodine and a length-reference based on a high-finesse ultra-stable optical cavity. Current efforts aim at a space compatible design of the two clocks and improving the long-term stability of the cavity reference. In a recently completed Phase A study, the feasibility of accommodating the mSTAR experiment on a SaudiSat 4 bus was investigated.