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Two-dimensional SnS emerged as a promising space material, with strong third-order optical nonlinearities maintained upon exposure to 60Co γ-rays at a dose equal to over 45 year accumulation in a typical earth orbit.

The ever-increasing space exploration enterprise calls for novel and high-quality radiation-resistant materials, among which nonlinear optical materials and devices are particularly scarce. Two-dimensional (2D) materials have shown promising potential, but the radiation effects on their nonlinear optical properties remain largely elusive. We previously fabricated 2D bismuthene for mode-locking sub-ns laser; herein, their space adaption was evaluated under a simulated space radiation environment. The as-synthesized thin layers of bismuthene exhibited strong third-order nonlinear optical responses extending into the near-infrared region. Remarkably, when exposed to 60Co γ-rays and electron irradiation, the bismuthene showed only slight degradation in saturable absorption behaviors that were critical for mode-locking in space. Ultrafast spectroscopy was applied to address the radiation effects and damage mechanisms that are difficult to understand by routine techniques. This work offers a new bottom-up approach for preparing 2D bismuthene, and the elucidation of its fundamental excited-state dynamics after radiation also provides a guideline to optimize the material for eventual space applications.

All-inorganic metal halide perovskites are a new emerging star following organometallic halide perovskites, thanks to their outstanding optoelectronic properties and relatively higher stability at the same time. Our group has contributed in this field through developing novel fabrication methods for perovskite micro/nano crystals, cesium lead halide perovskite quantum dots (CsPbX3 QDs) in particular, and investigating their photoinduced excited-state dynamics via various time-resolved spectroscopic techniques. Therefore in this chapter, we focus on the review of (nonlinear) optical properties and dynamics of CsPbX3 QDs. The chapter is organized as the followings: immediately after Sect. 6.1 of Introduction, Sect. 6.2 summarizes current preparation methods and focuses on mechanosynthesis (ball milling technique strategy), a methodology we are among the earliest groups to advocate. Section 6.3 details the photoinduced excited-state dynamics of perovskite QDs as fast as femtosecond (fs) scale, through different time-resolved spectroscopic tools including fluorescence lifetime measurement, fs transient absorption spectroscopy, streak camera, etc. Section 6.4 reviews the applications of CsPbX3 QDs stemming from their unique optical/electronic properties: optoelectronic devices, photocatalysis, nanolasers, and particularly nonlinear optics. The final Sect. 6.5 is Perspectives, which gives the thoughts for the future trend of the field from the authors. To sum up, all-inorganic perovskite QDs have thrived in the optoelectronic field. Numerous new experimental findings and applications of them are springing up every day. As an exciting new territory, there is much to be explored through joint efforts of researchers from varied background of physics, chemistry, optics, electronics, engineering, etc., through employing powerful methodologies like ultrafast spectroscopy.

Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power (Pmax) is presented and analyzed. The degradation at both electron energies has been correlated with the displacement damage dose (Dd). A good linearity between the electron Dd and the mean Pmax degradation is obtained. The concept of Dd has also been used to predict the Si solar cell response in a low-earth-orbit (Altitude 799 km, Inclination 99°) radiation environment, considering the shielded effect of a 120 μm-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite (duration from April 2007 to July 2010), a good match can be found between the on-orbit data and the predicted results using Dd methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.

The effect of space radiation environments on the degradation of triple-junction InGaP2/GaAs/Ge cells was studied to provide the reference for solar array design. The irradiationswere performedby the irradiation line-based unit-6 electron radiation facility. The solar cells were irradiated at room temperature with 0.8, 1, and 2 Mev electrons. For a given degradation level, the fluence level decreases for an increasing energy, indicating the higher energy electrons do relatively more damage. Degradation at different electron energies has been correlated with displacement damage dose. The performance of the triple-junction cells with various thicknesses of silica coverglass in a geostationaryEarth orbit radiation environment is presented. The power of the triple-junction cells will decrease to about 60%of the original value if uncovered by silica glass, while the use of a 500m-thick glass will decrease the endpower of the 15-yearmission by 30%of the original power. A 100m-thick silica glass (thickness usually used in space solar array) is not enough for blocking the electron radiation on the solar cells.

Photovoltaic solar arrays are preferably used as primary power source for majority of spacecraft today. The space radiation environment causes gradual solar cells performance degradation, thus limiting the lifetime of the solar array. In planning a space mission, engineers need to know the expected cell degradation in the space radiation environment, so a degradation model is required to predict the behaviors of solar cells in space. In this chapter, the irradiation experimental results were presented about silicon, single-junction and triple-junction GaAs solar cells, and thin film solar cells to compare radiation effects of electrons and protons on these solar cells, and also to provide experimental data for predictions of the cell performances. An approach developed by the US Naval Research Laboratory (NRL), also usually referred to as displacement damage dose methodology, is presented to predict triple-junction GaAs solar cell degradation using a particular case of protons and electrons irradiation. Enough information was presented to enable readers to make their own predictions for other solar cells using the method that works the best in a specific case. Compared to the on-orbit data from several satellite solar arrays, a good match can be found between the on-orbit data and the predicted results by NRL methodology, indicating the NRL method can provide the valuable reference for solar array design. However, the performance prediction of a-Si solar cells in space cannot be readily predicted by the NRL approach, and is still under discussion.

Space-graded single-junction (SJ) and triple-junction (TJ) GaAs solar cells, produced by MOCVD, are evaluated through electron-irradiation at the energy of 1MeV, 1.5MeV and 2MeV to compare radiation effects of electrons on these solar cells, and also to provide experimental data for predictions of the cell performances in space. Mean degradations of the short circuit current, open circuit voltage and maximum power are presented and analyzed. Compared to the radiation data of the single-junction GaAs cell, the triple-junction GaAs cell has a superior radiation-hardness performance at the same electron energy and fluence. Degradations at different electron energies have been correlated with displacement damage dose. A good linearity are obtained between the effective electron displacement damage dose and the degradation parameters. The performance prediction of both solar cells in space can be readily predicted by the approach.