150 research outputs found
Employing surfactant-assisted hydrothermal synthesis to control CuGaO2 nanoparticle formation and improved carrier selectivity of perovskite solar cells
Delafossites like CuGaO2 have appeared as promising p-type semiconductor
materials for opto-electronic applications mainly due to their high optical
transparency and electrical conductivity. However, existing synthetic efforts
usually result in particles with large diameter limiting their performance
relevant to functional electronic applications. In this article, we report a
novel surfactant-assisted hydrothermal synthesis method, which allows the
development of ultrafine (~5 nm) monodispersed p-type CuGaO2 nanoparticles
(NPs). We show that DMSO can be used as a ligand and dispersing solvent for
stabilizing the CuGaO2 NPs. The resulting dispersion is used for the
fabrication of dense, compact functional CuGaO2 electronic layer with
properties relevant to advanced optoelectronic applications. As a proof of
concept, the surfactant-assisted hydrothermal synthesized CuGaO2 is
incorporated as a hole transporting layer (HTL) in the inverted p-i-n
perovskite solar cell device architecture providing improved hole carrier
selectivity and power conversion efficiency compared to conventional PEDOT:PSS
HTL based perovskite solar cells
Room Temperature Nanoparticulate Interfacial Layers for Perovskite Solar Cells via solvothermal synthesis
We present a solvothermal synthetic route to produce monodispersed CuO
nanoparticles (NPs) in the range of 5-10 nm that can be used as hole selective
interfacial layer between indium tin oxide (ITO) and perovskite active layer
for p-i-n perovskite solar cells by a spin casting the dispersions at room
temperature. The bottom electrode interface modification provided by spherical
CuO-NPs at room temperature promotes the formation of high quality perovskite
photoactive layers with large crystal size and strong optical absorption.
Furthermore, it is shown that the nanoparticulate nature of the CuO hole
transporting interfacial layer can be used to improve light manipulation within
perovskite solar cell device structure. The corresponding p-i-n
CH3NH3PbI3-based solar cells show high Voc values of 1.09 V, which is
significantly higher compared to the Voc values obtained with conventional
PEDOT:PSS hole selective contact based perovskite solar cells
Long Thermal Stability of Inverted Perovskite Photovoltaics Incorporating Fullerene-based Diffusion Blocking Layer
In this article, the stability of p-i-n perovskite solar cells is studied
under accelerated heat lifetime conditions (60 oC ,85oC and N2 atmosphere). By
using a combination of buffer layer engineering, impedance spectroscopy and
other characterization techniques, we propose the interaction of the perovskite
active layer with the top Al metal electrode through diffusion mechanisms as
the major thermal degradation pathway for planar inverted perovskite
photovoltaics (PVs) under 85oC heat conditions. We show that by using thick
solution processed fullerene buffer layer the perovskite active layer can be
isolated from the top metal electrode and improve the lifetime performance of
the inverted perovskite photovoltaics at 85 oC. Finally, we present an
optimized solution processed inverted perovskite PV device using thick
fullerene-based diffusion blocking layer with over 1000 hours accelerated heat
lifetime performance at 60oC
Distribution of Visitor Use Management Research in US Wilderness from 2000 to 2020: A Scoping Review
Visitor use in wilderness has grown over the past several decades, along with research focused on visitor use management (VUM) in congressionally designated wilderness. This scoping review of research published between 2000 and 2020 explores the distribution and representativeness of wilderness VUM research within the context of (a) the federal land management agencies administering wilderness and (b) the geographic distribution of research. Findings indicate wilderness administered by the Bureau of Land Management and US Fish and Wildlife Service were disproportionately understudied compared to both the total acreage of wilderness and number of wilderness areas administered by the US Forest Service and National Park Service. Additionally, large geographic gaps exist in the research produced during this period, with clusters of VUM-related research occurring in high-profile wilderness areas and the vast majority (89%) of wilderness areas generating no research. As we look toward the next 20 years of wilderness VUM-related research, these findings suggest a need for a more representative narrative and highlight several specific opportunities for future research
Nanoparticulate Metal Oxide Top Electrode Interface Modification Improves the Thermal Stability of Inverted Perovskite Photovoltaics
Solution processed {\gamma}-Fe2O3 nanoparticles via the solvothermal
colloidal synthesis in conjunction with ligand-exchange method are used for
interface modification of the top electrode in inverted perovskite solar cells.
In comparison to more conventional top electrodes such as PC(70)BM/Al and
PC(70)BM/AZO/Al, we show that incorporation of a {\gamma}-Fe2O3 provides an
alternative solution processed top electrode (PC(70)BM/{\gamma}-Fe2O3/Al) that
not only results in comparable power conversion efficiencies but also improved
thermal stability of inverted perovskite photovoltaics. The origin of improved
stability of inverted perovskite solar cells incorporating PC(70)BM/
{\gamma}-Fe2O3/Al under accelerated heat lifetime conditions is attributed to
the acidic surface nature of {\gamma}-Fe2O3 and reduced charge trapped density
within PC(70)BM/ {\gamma}-Fe2O3/Al top electrode interfaces.Comment: 24 pages, 11 figure
Exploring Underserved Communities’ Perspectives on Wilderness Character in Everglades National Park
Issues related to diversity, equity, and inclusion are becoming increasingly important to park and protected area managers. Recently, several Executive Orders have established policies and priorities for steering public lands to better serve the diversity of the US public. Certain groups, compared to the US population at large, are underrepresented as visitors to parks and protected areas in the US, including BIPOC communities (Black, Indigenous, and other People of Color), women, people with disabilities, veterans, people with lower socioeconomic status, and the elderly. This disparity in visitation may be even more pronounced in federally designated wilderness areas. We present a qualitative study focused on the relationships of traditionally underserved groups with Everglades National Park, specifically focusing on perceptions of wilderness character in the Marjory Stoneman Douglas Wilderness. Findings illuminate both perceived benefits of wilderness, including positive mental health, ecosystem services, and a connection to unique aspects of wilderness character in the Everglades, as well as conflicted feelings about wilderness as a place that underemphasizes historic interactions of underrepresented communities with the landscape. We discuss management implications, particularly ways to focus protected area efforts to broaden the relevancy of wilderness lands and better serve diverse populations within local communities
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Dopa-Responsive Dystonia: Functional Analysis of Single Nucleotide Substitutions within the 5’ Untranslated GCH1 Region
Background: Mutations in the GCH1 gene are associated with childhood onset, dopa-responsive dystonia (DRD). Correct diagnosis of DRD is crucial, given the potential for complete recovery once treated with L-dopa. The majority of DRD associated mutations lie within the coding region of the GCH1 gene, but three additional single nucleotide sequence substitutions have been reported within the 5’ untranslated (5’UTR) region of the mRNA. The biologic significance of these 5’UTR GCH1 sequence substitutions has not been analyzed. Methodology/Principal Findings Luciferase reporter assays, quantitative real time PCR and RNA decay assays, combined with bioinformatics, revealed a pathogenic 5’UTR GCH1 substitution. The +142C>T single nucleotide 5’UTR substitution that segregates with affected status in DRD patients, substantially attenuates translation without altering RNA expression levels or stability. The +142C>T substitution disrupts translation most likely by creating an upstream initiation start codon (uAUG) and an upstream open reading frame (uORF). Conclusions/Significance: This is the first GCH1 regulatory substitution reported to act at a post-transcriptional level, increasing the list of genetic diseases caused by abnormal translation and reaffirming the importance of investigating potential regulatory substitutions in genetic diseases
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