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1. High grain boundary recombination velocity in polycrystalline metal halide perovskites

   https://doi.org/10.1126/sciadv.abq8345  

   Ni, Zhenyi; Xu, Shuang; Jiao, Haoyang; Gu, Hangyu; Fei, Chengbin; Huang, Jinsong (September 2022, Science Advances)

   Understanding carrier recombination processes in metal halide perovskites is fundamentally important to further improving the efficiency of perovskite solar cells, yet the accurate recombination velocity at grain boundaries (GBs) has not been determined. Here, we report the determination of carrier recombination velocities at GBs (S_GB) of polycrystalline perovskites by mapping the transient photoluminescence pattern change induced by the nonradiative recombination of carriers at GBs. Charge recombination at GBs is revealed to be even stronger than at surfaces of unpassivated films, with averageS_GBreaching 2200 to 3300 cm/s. Regular surface treatments do not passivate GBs because of the absence of contact at GBs. We find a surface treatment using tributyl(methyl)phosphonium dimethyl phosphate that can penetrate into GBs by partially dissolving GBs and converting it into one-dimensional perovskites. It reduces the averageS_GBby four times, with the lowestS_GBof 410 cm/s, which is comparable to surface recombination velocities after passivation. 

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2. High Heterogeneity in Canopy Temperature Among Co‐occurring Tree Species in a Temperate Forest

   https://doi.org/10.1029/2020JG005892  

   Yi, Koong; Smith, Jake W.; Jablonski, Andrew D.; Tatham, Elizabeth A.; Scanlon, Todd M.; Lerdau, Manuel T.; Novick, Kimberly A.; Yang, Xi (December 2020, Journal of Geophysical Research: Biogeosciences)

   Abstract Trees regulate canopy temperature (T_c) via transpiration to maintain an optimal temperature range. In diverse forests such as those of the eastern United States, the sensitivity ofT_cto changing environmental conditions may differ across species, reflecting wide variability in hydraulic traits. However, these links are not well understood in mature forests, whereT_cdata have historically been difficult to obtain. Recent advancement of thermal imaging cameras (TICs) enablesT_cmeasurement of previously inaccessible tall trees. By leveraging TIC and sap flux measurements, we investigated how co‐occurring trees (Quercus alba,Q. falcata, andPinus virginiana) change theirT_cand vapor pressure deficit near the canopy surface (VPD_c) in response to changing air temperature (T_a) and atmospheric VPD (VPD_a). We found a weaker cooling effect for the species that most strongly regulates stomatal function during dry conditions (isohydric;P. virginiana). Specifically, the pine had higherT_c(up to 1.3°C) and VPD_c(up to 0.3 kPa) in the afternoon and smaller sensitivity of both∆T(=T_c − T_a) and∆VPD (=VPD_c − VPD_a) to changing conditions. Furthermore, significant differences inT_cand VPD_cbetween sunlit and shaded portions of a canopy implied a non‐evaporative effect onT_cregulation. Specifically,T_cwas more homogeneous within the pine canopy, reflecting differences in leaf morphology that allow higher canopy transmittance of solar radiation. The variability ofT_camong species (up to 1.3°C) was comparable to the previously reported differences in surface temperature across land cover types (1°C to 2°C), implying the potential for significant impact of species composition change on local/regional surface temperature. 

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3. Lyα Escape from Low-mass, Compact, High-redshift Galaxies

   https://doi.org/10.3847/1538-3881/ac83a9  

   Pucha, Ragadeepika; Reddy, Naveen A.; Dey, Arjun; Juneau, Stéphanie; Lee, Kyoung-Soo; Prescott, Moire K.; Shivaei, Irene; Hong, Sungryong (September 2022, The Astronomical Journal)

   Abstract We investigate the effects of stellar populations and sizes on Lyαescape in 27 spectroscopically confirmed and 35 photometric Lyαemitters (LAEs) atz≈ 2.65 in seven fields of the Boötes region of the NOAO Deep Wide-Field Survey. We use deep HST/WFC3 imaging to supplement ground-based observations and infer key galaxy properties. Compared to typical star-forming galaxies (SFGs) at similar redshifts, the LAEs are less massive (M_⋆≈ 10⁷–10⁹M_⊙), younger (ages ≲1 Gyr), smaller (r_e< 1 kpc), and less dust-attenuated (E(B−V) ≤ 0.26 mag) but have comparable star formation rates (SFRs ≈ 1–100M_⊙yr⁻¹). Some of the LAEs in the sample may be very young galaxies having low nebular metallicities (Z_neb≲ 0.2Z_⊙) and/or high ionization parameters ( $\log \left(\mathrm{U}\right)\gtrsim -2.4$). Motivated by previous studies, we examine the effects of the concentration of star formation and gravitational potential on Lyαescape by computing SFR surface density, Σ_SFR, and specific SFR surface density, Σ_sSFR. For a given Σ_SFR, the Lyαescape fraction is higher for LAEs with lower stellar masses. The LAEs have a higher Σ_sSFR, on average, compared to SFGs. Our results suggest that compact star formation in a low gravitational potential yields conditions amenable to the escape of Lyαphotons. These results have important implications for the physics of Lyαradiative transfer and for the type of galaxies that may contribute significantly to cosmic reionization. 

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4. Direct upcycling of degraded NCM via low-temperature surface engineering for high performance lithium-ion batteries

   https://doi.org/10.1039/D5EB00018A  

   Wang, Yu; Yuan, Chris (August 2025, EES Batteries)

   This paper introduces the upcycling process of degraded NCM particlesviasurface engineering to restore the crystal structure, enhance the electrochemical performance, and improve the thermal stability. 

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5. Multi‐Sensor Approach for High Space and Time Resolution Land Surface Temperature

   https://doi.org/10.1029/2021EA001842  

   Desai, Ankur R.; Khan, Anam M.; Zheng, Ting; Paleri, Sreenath; Butterworth, Brian; Lee, Temple R.; Fisher, Joshua B.; Hulley, Glynn; Kleynhans, Tania; Gerace, Aaron; et al (October 2021, Earth and Space Science)

   Abstract Surface‐atmosphere fluxes and their drivers vary across space and time. A growing area of interest is in downscaling, localizing, and/or resolving sub‐grid scale energy, water, and carbon fluxes and drivers. Existing downscaling methods require inputs of land surface properties at relatively high spatial (e.g., sub‐kilometer) and temporal (e.g., hourly) resolutions, but many observed land surface drivers are not continuously available at these resolutions. We evaluate an approach to overcome this challenge for land surface temperature (LST), a World Meteorological Organization Essential Climate Variable and a key driver for surface heat fluxes. The Chequamegon Heterogenous Ecosystem Energy‐balance Study Enabled by a High‐density Extensive Array of Detectors (CHEESEHEAD19) field experiment provided a scalable testbed. We downscaled LST from satellites (GOES‐16 and ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station [ECOSTRESS]) with further refinement using airborne hyperspectral imagery. Temporally and spatially downscaled LST compared well to independent observations from a network of 20 micrometeorological towers and piloted aircrafts in addition to Landsat‐based LST retrieval and drone‐based LST observed at one tower site. The downscaled 50‐m hourly LST showed good relationships with tower (r² = 0.79, RMSE = 3.5 K) and airborne (r² = 0.75, RMSE = 2.4 K) observations over space and time, with precision lower over wetlands and lakes, and some improvement for capturing spatio‐temporal variation compared to a geostationary satellite. Further downscaling to 10 m using hyperspectral imagery resolved hot and cold spots across the landscape as evidenced by independent drone LST, with significant reduction in RMSE by 1.3 K. These results demonstrate a simple pathway for multi‐sensor retrieval of high space and time resolution LST. 

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