Time-resolved photoluminescence (TRPL) spectroscopy is a powerful technique to investigate excited charge carrier recombinations in semiconductors and molecular systems. The analysis of the TRPL ...decays of many molecular systems (
e.g.
molecules and organic materials) is usually fairly straightfoward and can be fitted with an exponential function allowing extraction of the rate constants. Due to the non-excitonic nature of charge carriers in lead halide perovskite materials coupled with the presence of localised trap states in their band-gap, the TRPL of these materials is much more complicated to interpret. Here we discuss two models used in the literature to simulate charge carrier recombinations and TRPL in perovskites. These models consider the bimolecular nature of direct electron-hole recombination but differ in their treatment of trap-mediated recombination with one model describing trapping as a monomolecular process whereas the other as a bimolecular process between free carriers and the available trap states. In comparison, the classical analysis of perovskite TRPL decay curves (using a sum of exponentials) can lead to misinterpretation. Here we offer some recommendations for meaningful measurements of lead halide perovskite thin-films. The fluence dependence as well as charge carrier accumulation due to incomplete depopulation of all photoexcited carriers between consecutive excitation pulses are discussed for both models.
Evaluation of commonly used models to fit the TRPL of perovskites; retrieving meaningful data requires careful choice of excitation fluence.
Lead halide perovskite solar cells (PSCs) are an emerging solar photovoltaic (PV) technology on the cusp of commercialisation, promising to deliver the lowest cost solar energy to date (<32 $ per MW ...h). Owing to the required scale of PV deployment to mitigate climate change, potential limits to deployment due to materials criticality issues, and the necessity to prevent impacts from PV waste, adoption of circular economy is essential for perovskite technologies. Here we examine 3 key themes to inform future development towards commercialisation: legislative and economic drivers for adoption of circular economy by the emerging perovskite PV industry; environmental and future materials supply issues; and current state of research which may enable remanufacturing and recycling strategies to facilitate circular utilisation of key materials in successive product generations.
We examine drivers and benefits of adopting circular economy practices for perovskite solar cells (PSCs), a promising low-cost PV technology, identifying key challenges and reviewing research progress towards achieving a circular economy for PSCs.
An extremely fast annealing technique for mixed-halide perovskite solar cells is presented. Using photonic flash sintering, we have demonstrated that a spin-coated perovskite precursor may be fully ...annealed in as little as 1 ms. Devices annealed in 1.15 ms yielded power conversion efficiencies (PCEs) of upto 11.3% compared to 15.2% for samples annealed for 90 minutes on a hotplate.
Organolead trihalide perovskite solar cells based upon the co-deposition of a combined Al2O3-perovskite layer at T < 110 °C are presented. We report an average PCE = 7.2% on a non-sintered Al2O3 ...scaffold in devices that have been manufactured from a perovskite precursor containing 5 wt% Al2O3 nanoparticles.
Cortical hand strokes affect the ‘hand knob’ of the motor cortex, resulting in isolated distal upper limb or hand weakness. They are rare and can be easily misdiagnosed for peripheral lesions.
Case ...1: A 59-year-old man presented to the Emergency Department (ED) after noticing left hand weakness while driving. There was no sensory deficit noted. A full neurological examination suggested an upper motor neurone rather than a peripheral nerve lesion. This was confirmed by a magnetic resonance imaging scan of his brain. Case 2: An 88-year-old man presented to the ED after developing sudden-onset left hand weakness while completing a newspaper puzzle. Power returned gradually over approximately 4 h, with no sensory symptoms being noted. A transient ischemic attack leading to cortical hand was diagnosed.
Cortical hand strokes are a rare, but important, differential for wrist drop. They are often first strokes and embolic in nature. Therefore, correct diagnosis is vital to enable initiation of secondary prevention.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Photovoltaics (PV) are increasingly important for electrification in rural Sub-Saharan Africa, but what is the best battery technology to use? To explore this question, a small-scale domestic PV ...system for South Africa (20-year lifetime) to deliver 1.42 kWh electricity from batteries overnight with 10-h discharge was costed with various Li-ion, Pb-acid and Aquion aqueous hybrid ion batteries (AHIBs). Environmental impact; compatibility with circular economy; potential for cost-reduction through lifetime extension; and valorisation of batteries at end-of-life is discussed. Batteries are 81–93% of system costs, and battery production required over the system lifetime would emit 743, 674 and 6060 kg CO2-eq (Pb-acid, Li-ion and AHIBs respectively). Hazardous materials in Li-ion and Pb-acid batteries pose risks at end-of-life. Li-ion and AHIBs face potential resource supply constraints due to use of Co, Li and graphite. Closed-loop recycling and refurbishment of Pb-acid batteries is well established in South Africa. Currently, no African facilities for Li-ion or AHIB recycling exist, with little opportunity to retain material value from these batteries within the region. Despite lower efficiencies and shorter lifetimes, Pb-acid batteries, which are readily available from domestic manufacturing at low cost, are the current best choice for sustainable small-scale domestic PV systems in South Africa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Treatment with androgen receptor pathway inhibitors (ARPIs) in prostate cancer leads to the emergence of resistant tumors characterized by lineage plasticity and differentiation toward neuroendocrine ...lineage. Here, we find that ARPIs induce a rapid epigenetic alteration mediated by large-scale chromatin remodeling to support activation of stem/neuronal transcriptional programs. We identify the proneuronal transcription factor ASCL1 motif to be enriched in hyper-accessible regions. ASCL1 acts as a driver of the lineage plastic, neuronal transcriptional program to support treatment resistance and neuroendocrine phenotype. Targeting ASCL1 switches the neuroendocrine lineage back to the luminal epithelial state. This effect is modulated by disruption of the polycomb repressive complex-2 through UHRF1/AMPK axis and change the chromatin architecture in favor of luminal phenotype. Our study provides insights into the epigenetic alterations induced by ARPIs, governed by ASCL1, provides a proof of principle of targeting ASCL1 to reverse neuroendocrine phenotype, support luminal conversion and re-addiction to ARPIs.
Zero-valent copper (Cu0) is a promising co-catalyst in semiconductor-based photocatalysis as it is inexpensive and exhibits electronic properties similar to those of Ag and Au. However, its practical ...application in photocatalytic hydrogen production is limited by its susceptibility to oxidation, forming less active Cu species. Herein, we have carried out in situ encapsulation of Cu0 nanoparticles with N-graphitic carbon layers (14.4% N) to stabilize Cu0 nanoparticles (N/C-coated Cu) and improve the electronic communication with a TiO2 photocatalyst. A facile solvothermal procedure is used to coat the Cu0 nanoparticles at 200 °C, while graphitization is achieved by calcination at 550 °C under an inert atmosphere. The resultant N/C-coated Cu/TiO2 composites outperform the uncoated Cu counterparts, exhibiting a 27-fold enhancement of the hydrogen evolution rate compared to TiO2 and achieving a rate of 19.03 mmol g–1 h–1 under UV–vis irradiation. Likewise, the N/C-coated Cu co-catalyst exhibits a less negative onset potential of −0.05 V toward hydrogen evolution compared to uncoated Cu (ca. −0.30 V). This superior activity is attributed to coating Cu0 with N/C, which enhances the stability, electronic communication with TiO2, conductivity, and interfacial charge transfer processes. The reported synthetic approach is simple and scalable, yielding an efficient and affordable Cu0 co-catalyst for TiO2.
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IJS, KILJ, NUK, PNG, UL, UM
A rapid annealing technique for CH
3
NH
3
PbI
3
perovskite solar cells is presented. We report a co-deposited Al
2
O
3
-perovskite device annealed in under 2.5 seconds with a PCE of 10.0% compared to ...10.9% for a 45 minute oven-annealed device.
A rapid annealing technique for CH
3
NH
3
PbI
3
perovskite solar cells is presented.
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