Antioxidative solution processing yields exceptional Sn(Ⅱ) stability for sub-1.4 eV bandgap inorganic perovskite solar cells

Owing to the combined features of sub-1.4 eV bandgap and all-inorganic composition,cesium tin–lead(Sn-Pb)triiodide perovskite is promising for approaching the Shockley-Queisser limit of solar cells while avoiding the use of volatile organic cations.But the low Sn(Ⅱ)stability in this perovskite remains a hurdle for delivering its theoretically attainable device performance.Herein we present a synthesis method of this perovskite based on an acetylhydrazine-incorporated antioxidative solution system.Mechanistic investigation shows that acetylhydrazine effectively reduces the oxidation of solution-phase Sn(Ⅱ)and meanwhile creates an electron-rich,protective nano-environment for solid-state Sn(Ⅱ)ions.These lead to high oxidation resistance of the final film as well as effective defect inhibition.The resultant solar cells demonstrate power conversion efficiencies up to 15.04%,the highest reported so far for inorganic perovskite devices with sub-1.4 eV bandgaps.Furthermore,the T_(90) lifetime of these devices can exceed 1000 hours upon light soaking in a nitrogen atmosphere,demonstrating the potential advantage when lower-bandgap perovskite solar cells go all-inorganic.

D-π-D molecular layer electronically bridges the NiO_(x) hole transport layer and the perovskite layer towards high performance photovoltaics

Nickel oxide (NiO_(x)) has significant cost and stability advantages over poly[bis (4-phenyl)(2,4,6-trimethyl phenyl)amine](PTAA) for inverted p-i-n perovskite solar cells (PSCs),but the poor NiO_(x)/perovskite contact stemming from some reactive species at the interface led to suboptimal device performance.To solve this problem,we take a multiple donor molecule approach,using 3,3’-(4,8-bis(hexylthio)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl)bis(10-(6-bromohexyl)-10H-phenoxazine)(BDT-POZ) as an example,to modify the NiO_(x)/perovskite interface.The primary goal was to reduce the under-coordinated Ni^(≥3+) cations via electron transfer from the donor molecules to NiO_(x),thus mitigating the detrimental reactions between perovskite and NiO_(x).Equally importantly,the hole extraction at the interface was greatly enhanced after the organic donor modification,since the hydrophobic species atop NiO_(x) not only enabled pinhole-free crystallization of the perovskite but also properly tuned the interfacial energy level alignment.Consequently,the PSCs with NiO_(x)/BDT-POZ HTL achieved a high power conversion efficiency (PCE) up to 20.16%,which compared excellently with that of the non-modified devices (17.83%).This work provides a new strategy to tackle the exacting issues that have so far impeded the development of NiO_(x) based PSCs.

Silicon photonic spectrometer with multiple customized wavelength bands

A silicon photonic spectrometer with multiple customized wavelength bands is developed by introducing multiple channels of wideband optical filters based on multimode waveguide gratings(MWGs)for pre-filtering and the corresponding thermally tunable narrowband filter for high resolution.For these multiple customized wavelength bands,the central wavelengths,bandwidths,and resolutions are designed flexibly as desired,so that the system is simplified and the footprint is minimized for several practical applications(e.g.,gas sensing).A customized silicon photonic spectrometer is designed and demonstrated experimentally with four wavelength bands centered around1310 nm,1560 nm,1570 nm,and 1930 nm,which is,to the best of our knowledge,the first on-chip spectrometer available for sensing multiple gas components like HF,CO,H_(2)S,and CO_(2).The spectral resolutions of the four wavelength bands are 0.11 nm,0.08 nm,0.08 nm,and 0.37 nm,respectively.Such a customized silicon photonic spectrometer shows great potential for various applications,including gas monitors,wearable biosensors,and portable spectral-domain optical coherence tomography.

Materials and structures for the electron transport layer of efficient and stable perovskite solar cells

The electron transport layer plays a vital function in extracting and transporting photogenerated electrons, modifying the interface, aligning the interfacial energy level and minimizing the charge recombination in perovskite solar cells. This review summarizes the recent research progress on electron transport materials of metal oxides, organic molecules and multilayers. The doped metal oxides as electron transport materials in regular perovskite solar cells show improved device performance relative to their non-doped counterpart due to enhanced electron mobility and energy level alignment. The non-fullerene organic electron transport materials with better electron mobility and tunable energy level alignment need to be further designed and developed despite their advantages of mechanical flexibility and wide range tunability. The multilayer electron transport materials are suggested to be an important direction of research for efficient and stable perovskite solar cells because of their favorable synergistic interaction.

Two-step solvent post-treatment on PTAA for highly efficient and stable inverted perovskite solar cells

Modifying the surface of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)with toluene during the high-speed spin-coating process of dimethylformamide considerably improves the wettability and morphology of PTAA and results in improvement of the crystallinity and absorption of perovskite film.The hole mobility and ohm contact have also been improved accordingly.Combined with these improved parameters,inverted perovskite solar cells with high efficiency of 19.13%and long-term stability could be achieved,which are much better than those with untreated PTAA.Importantly,our devices can keep 88.4%of the initial power conversion efficicncy after 30 days of storage in ambient air.

How a single receptor‑like kinase exerts diverse roles:lessons from FERONIA

FERONIA(FER)is a member of the Catharanthus roseus receptor-like kinase 1-like(CrRLK1L)protein subfamily,which participates in reproduction,abiotic stress,biotic stress,cell growth,hormone response,and other molecular mecha-nisms of plants.However,the mechanism by which a single RLK is capable of mediating multiple signals and activat-ing multiple cellular responses remains unclear.Here,we summarize research progress revealing the spatial–temporal expression of FER,along with its co-receptors and ligands determined the function of FER signaling pathway in multiple organs.The specificity of the FER signaling pathway is proposed to operate under a four-layered mechanism:(1)Spatial–temporal expression of FER,co-receptors,and ligands specify diverse functions,(2)Specific ligands or ligand combinations trigger variable FER signaling pathways,(3)Diverse co-receptors confer diverse FER perception and response modes,and(4)Unique downstream components that modify FER signaling and responses.Moreover,the regulation mechanism of the signaling pathway-appears to depend on the interaction among the ligands,RLK receptors,co-receptors,and downstream components,which may be a general mechanism of RLKs to maintain signal specificity.This review will provide a insight into understanding the specificity determination of RLKs signaling in both model and horticultural crops.

The ABA-AtNAP-SAG113 PP2C module regulates leaf senescence by dephoshorylating SAG114 SnRK3.25 in Arabidopsis

We previously reported that ABA inhibits stomatal closure through AtNAP-SAG113 PP2C regulatory module during leaf senescence.The mechanism by which this module exerts its function is unknown.Here we report the identification and functional analysis of SAG114,a direct target of the regulatory module.SAG114 encodes SnRK3.25.Both bimolecular fluorescence complementation(BiFC)and yeast two-hybrid assays show that SAG113 PP2C physically interacts with SAG114 SnRK3.25.Biochemically the SAG113 PP2C dephosphorylates SAG114 in vitro and in planta.RT-PCR and GUS reporter analyses show that SAG114 is specifically expressed in senescing leaves in Arabidopsis.Functionally,the SAG114 knockout mutant plants have a significantly bigger stomatal aperture and a much faster water loss rate in senescing leaves than those of wild type,and display a precocious senescence phenotype.The premature senescence phenotype of sag114 is epistatic to sag113(that exhibits a remarkable delay in leaf senescence)because the sag113 sag114 double mutant plants show an early leaf senescence phenotype,similar to that of sag114.These results not only demonstrate that the ABA-AtNAP-SAG113 PP2C regulatory module controls leaf longevity by dephosphorylating SAG114 kinase,but also reveal the involvement of the SnRK3 family gene in stomatal movement and water loss during leaf senescence.