Improving morphology and optoelectronic properties of ultra-wide bandgap perovskite via Cs tuning for clear solar cell and UV detection applications.

With growing population, vertical spaces from skyscrapers are vast. Semi-transparent solar cells enable an effective pathway for vertical energy harvesting. With composition tunability, perovskite materials can be designed with different transparencies and colors. In this work, an ultra-high bandgap layered triple cation perovskite system was developed for the first time to meet the demand of clear optoelectronic applications; low dimensional triple cation perovskite thin films were fabricated using perovskite with the formula (PEA)2(CsxMA0.61-xFA0.39)39(Pb)40(Cl0.88-0.32xBr0.12+0.32x)121, 0 ≤ x ≤ 0.02 with DMSO as the appropriate solvent. The absorption edge of the material is around 410-430 nm, achieving great transparency to visible light. The structural, optical, and photovoltaic performances of the clear perovskite materials are explored with the variation of Cs contents via CsBr. The relation between thickness, transparency, and optoelectronic properties of the clear perovskite materials along with other physical properties were investigated. The highest photovoltaic conversion efficiency (PCE) of clear perovskite solar cells with 1.5% Cs was achieved to be 0.69% under xenon lamp irradiation at 100 mW/cm2 (1.5 mW/cm2 of UVA within 100 mW/cm2) and 5.24% under 365 nm UV irradiation at 2.4 mW/cm2. Photoresponsivity, external quantum efficiency (EQE), and detectivity were also determined for photodetector applications.

Graded multilayer triple cation perovskites for high speed and detectivity self-powered photodetector via scalable spray coating process.

Rapid advancements in perovskite materials have led to potential applications in various optoelectronic devices, such as solar cells, light-emitting diodes, and photodetectors. Due to good photoelectric properties, perovskite enables low-cost and comparable performance in terms of responsivity, detectivity, and speed to those of the silicon counterpart. In this work, we utilized triple cation perovskite, well known for its high performance, stability, and wide absorption range, which is crucial for broadband photodetector applications. To achieve improved detectivity and faster response time, graded multilayer perovskite absorbers were our focus. Sequential spray deposition, which allows stacked perovskite architecture without disturbing lower perovskite layers, was used to generate single, double, and triple-layer perovskite photodetectors with proper energy band alignment. In this work, we achieved a record on self-powered perovskite photodetector fabricated from a scalable spray process in terms of EQE and responsivity of 65.30% and 0.30 A W-1. The multilayer devices showed faster response speed than those of single-layer perovskite photodetectors with the champion device reaching 70 µs and 88 µs for rising and falling times. The graded band structure and the internal electric field generated from perovskite heterojunction also increase specific detectivity about one magnitude higher in comparison to the single-layer with the champion device achieving 6.82 × 1012 cmHz1/2 W-1.

Thylacopterisminuta (Polypodiaceae), a new fern species from Myanmar.

The genus Thylacopteris is a small, phylogenetically isolated genus belonging to the fern family Polypodiaceae. This study describes a new species, Thylacopterisminuta, based on collections obtained during field surveys of Shan State, Myanmar. This new species is distinct from other species of Thylacopteris in its small size and presence of sclerenchyma strands in the rhizome. This species is also distinct from the only other species of Thylacopteris with molecular data available, T.papillosa, in a plastid rbcL phylogeny of Polypodiaceae. This new discovery of Thylacopteris from Myanmar suggests that this genus is still overlooked in Southeast Asia.

Lepisorusmedioximus (Polypodiales, Polypodiaceae), a new species from Shan State of Myanmar.

A new species of the species-rich fern genus Lepisorus (Polypodiales, Polypodiaceae) has been found to occur in Shan state, Myanmar. Lepisorusmedioximus is described based on morphological characters and phylogenetic evidence. Phylogenetic analyses showed that the specimens of L.medioximus formed a distinct clade nested in the Pseudovittaria clade. The morphological comparison demonstrated that the species is distinct from phylogenetically related species, namely L.elegans, L.contortus, and L.tosaensis, in the morphology of the rhizome scales, size, and shape of the lamina, position of sori, and paraphyses.

Traditional knowledge of wild edible plants with special emphasis on medicinal uses in Southern Shan State, Myanmar.

BACKGROUND: Myanmar is one of the hotspots of biodiversity and is a rapidly developing country. Performing floristic research in Myanmar is an urgent issue, and ethnobotanical studies of wild edible plants (WEPs) will provide new information on natural plant resources. METHOD: Ethnobotanical data were collected in three villages with different historical backgrounds in Southern Shan State, Myanmar. A total of 19 key informants were interviewed, and specimens were collected in the fields with the participation of key informants in June-July 2015. Group discussions were organized during 2016 and 2017 to reinforce the information on use of WEPs. DNA barcoding was used to facilitate species identification. RESULTS: A total of 83 species from 44 families of angiosperms were recorded as WEPs. Most of the species were used as wild vegetables (47 species), followed by fruits and nuts (31 species). Eighteen WEPs were consumed as medicinal foods. Differences in use of WEPs between the communities of the villages were observed. The age class of 30-39 years was more familiar with the environments where they could collect WEPs and had more knowledge of WEPs than did the older groups. The use of Elaeocarpus floribundus as an edible oil is a very interesting tradition. CONCLUSION: WEPs play an important role in the livelihood of local communities. The indigenous society has maintained traditional knowledge of the WEPs. Historical background, land use system and surrounding vegetation could have effects on the variation in the traditional uses of WEPs. Increasing awareness of the importance of WEPs will encourage the conservation of traditional knowledge of indigenous populations.