Tin(II) Acetylacetonate as a New Type of Tin Compensator Additive for Tin-Based Perovskite Solar Cells.

Tin (Sn)-based perovskite is one of the most promising candidates for lead (Pb)-free perovskite light-absorbing materials applied in solar cells. However, the intrinsic Sn vacancy (VSn) defects seriously hinder the device performance, making the reported maximum power efficiency (PCE) of Sn-based perovskite solar cells (PSCs) far behind those of Pb-based ones. During the study, SnF2 has been demonstrated as an indispensable Sn compensator additive to improve the device performance. Considering that the default use of SnF2 and the selection of a Sn compensator has also been limited to tin(II) halides, i.e., SnCl2, SnBr2, and SnI2, the role and work mechanism of the Sn compensator have not yet been clarified clearly. Herein, a new type of Sn compensator, tin(II) acetylacetonate [Sn (acac)2], is introduced into Sn-based PSCs. It is found that in addition to tin compensation, the organic ligand acac- can coordinate with Sn2+ in the precursor solution and improve the crystallization process of perovskites. Consequently, the maximum PCE of formamidinium tin triiodide (FASnI3) solar cells is enhanced from 3.88 to 7.27% using Sn (acac)2 as the Sn compensator.

Self-Repairing Tin-Based Perovskite Solar Cells with a Breakthrough Efficiency Over 11.

The development of tin (Sn)-based perovskite solar cells (PSCs) is hindered by their lower power conversion efficiency and poorer stability compared to the lead-based ones, which arise from the easy oxidation of Sn2+ to Sn4+ . Herein, phenylhydrazine hydrochloride (PHCl) is introduced into FASnI3 (FA = NH2 CH  NH2 + ) perovskite films to reduce the existing Sn4+ and prevent the further degradation of FASnI3 , since PHCl has a reductive hydrazino group and a hydrophobic phenyl group. Consequently, the device achieves a record power conversion efficiency of 11.4% for lead-free PSCs. Besides, the unencapsulated device displays almost no efficiency reduction in a glove box over 110 days and shows efficiency recovery after being exposed to air, due to a proposed self-repairing trap state passivation process.

Mixed-Organic-Cation Tin Iodide for Lead-Free Perovskite Solar Cells with an Efficiency of 8.12.

In this work, a fully tin-based, mixed-organic-cation perovskite absorber (FA) x (MA)1-x SnI3 (FA = NH2CH = NH2+, MA = CH3NH3+) for lead-free perovskite solar cells (PSCs) with inverted structure is presented. By optimizing the ratio of FA and MA cations, a maximum power conversion efficiency of 8.12% is achieved for the (FA)0.75(MA)0.25SnI3-based device along with a high open-circuit voltage of 0.61 V, which originates from improved perovskite film morphology and inhibits recombination process in the device. The cation-mixing approach proves to be a facile method for the efficiency enhancement of tin-based PSCs.

A Breakthrough Efficiency of 19.9% Obtained in Inverted Perovskite Solar Cells by Using an Efficient Trap State Passivator Cu(thiourea)I.

It is extremely significant to study the trap state passivation and minimize the trap states of perovskite to achieve high-performance perovskite solar cells (PSCs). Here, we have first revealed and demonstrated that a novel p-type conductor Cu(thiourea)I [Cu(Tu)I] incorporated in perovskite layer can effectively passivate the trap states of perovskite via interacting with the under-coordinated metal cations and halide anions at the perovskite crystal surface. The trap state energy level of perovskite can be shallowed from 0.35-0.45 eV to 0.25-0.35 eV. In addition, the incorporated Cu(Tu)I can participate in constructing the p-i bulk heterojunctions with perovskite, leading to an increase of the depletion width from 126 to 265 nm, which is advantageous for accelerating hole transport and reducing charge carrier recombination. For these two synergistic effects, Cu(Tu)I can play a much better role than that of the traditional p-type conductor CuI, probably due to its identical valence band maximum with that of perovskite, which enables to not only lower the trap state energy level to a greater extent but also eliminate the potential wells for holes at the p-i heterojunctions. After optimization, a breakthrough efficiency of 19.9% has been obtained in the inverted PSCs with Cu(Tu)I as the trap state passivator of perovskite.

Generation of artificial sequence-specific nucleases via a preassembled inert-template.

Sequence specific nucleases are important tools for processing nucleic acids in a predictable way. Herein, we demonstrate a conceptually new approach for generating sequence-specific nucleases via a preassembled inert-template (PAIT). A fairly stable DNase I/inert-DNA complex was prepared with a customized sequence specificity for a target DNA which contains a sequence complementary to the inert-DNA template. The complex could efficiently cleave the targeted sequence within either a long double-stranded DNA or a single-stranded DNA without affecting other unrelated DNA strands. The discrimination factor against single-base mismatch strands within a 14 nt target region was as high as 25.3. The strategy was also successfully applied to RNase A. Our findings may hold great potential for the development of a number of new powerful enzymatic tools.

Sensitive discrimination of stable mismatched base pairs by an abasic site modified fluorescent probe and lambda exonuclease.

An abasic site modified fluorescent probe has been developed which enabled the rapid discrimination of stable single mismatched base pairs by lambda exonuclease with remarkably high discrimination factors (447 for T:G and 238 for A:G). This method allowed sensitive detection of single nucleotide variation at very low abundances (0.02-0.05% mutant-to-wild type).

In vivo and continuous measurement of bisulfide in the hippocampus of rat's brain by an on-line integrated microdialysis/droplet-based microfluidic system.

An on-line and continuous approach was demonstrated for in vivo measurement of bisulfide in rat's brain. A modified droplet-based microfluidic system was constructed, which allowed on-line qualification of the fluorescence responses of the gold nanoparticle-glutathione-fluorescein isothiocyanate probe to the variation of bisulfide in the presence of the cerebral microdialysate background. The on-line method achieved a dynamic working range from 5.0 µM to 40 µM and a detection limit of 2.5 µM. The in vivo bisulfide concentration in the hippocampus of rat's brain was measured under different physiological conditions. The on-line method may facilitate the study of H2S biology by providing a previously unattainable continuous record of H2S variation in living animals. It also provides a practical platform for in vivo and continuous monitoring of other important species in cerebral systems.