Improving the operational stability of perovskite solar cells with cesium-doped graphene oxide interlayer

Perovskite solar cells(PSCs)have made great advances in terms of power conversion efficiency(PCE),yet their subpar stability continues to hinder their commercialization.The interface between the perovskite layer and the charge-carrier transporting layers plays a crucial role in undermining the stability of PSCs.In this work,we propose a strategy to stabilize high-performance PSCs with PCE over 23%by introducing a cesium-doped graphene oxide(GO-Cs)as an interlayer between the perovskite and hole-transporting material.The GO-Cs treated PSCs exhibit excellent operational stability with a projected T80(the time where the device PCE reduces to 80%of its initial value)of 2143 h of operation at the maximum powering point under one sun illumination.

Retrograde inspection vs standard forward view for the detection of colorectal adenomas during colonoscopy: A back-to-back randomized clinical trial

BACKGROUND The adenoma detection rate(ADR)is inversely associated with the incidence of interval colorectal cancer and serves as a benchmark quality criterion during screening colonoscopy.However,adenoma miss rates reach up to 26%and studies have shown that a second inspection of the right colon in retroflected view(RFV)can increase ADR.AIM To assess whether inspection of the whole colon in RFV compared to standard forward view(SFV)can increase ADR.METHODS Patients presenting for screening or surveillance colonoscopy were invited to participate in this randomized controlled trial and randomized into two arms.In RFV arm colonoscopy was initially performed with SFV,followed by a second inspection of the whole colon in RFV.In the SFV arm first withdrawal was performed with SFV,followed by a second inspection of the whole colon again with SFV.Number,size and morphology of polyps found during first and second inspection in each colonic segment were recorded and all polyps were removed and sent for histopathology in separate containers.RESULTS Two hundred and five patients were randomly assigned to the RFV(n=101)and SFV(n=104)arm.In the RFV arm,both polyp detection rate(PDR)and ADR were increased under second inspection in RFV(PDR 1st SFV:39.8%,PDR 2nd RFV:46.6%;ADR 1st SFV:35.2%,ADR 2nd RFV:42%).Likewise,in the SFV arm,PDR and ADR were increased under second inspection(PDR 1st SFV:37.5%,PDR 2nd SFV:46.6%;ADR 1st SFV:34.1%,ADR 2nd SFV:44.3%)with no significant differences in ADR and PDR between the SFV and RFV arm.Mean number of adenomas per patient(APP)was increased in the RFV and SFV(APP RFV arm:1st SFV:1.71;2nd RFV:2.38;APP SFV arm:1st SFV:1.83,2nd SFV:2.2).The majority of adenomas additionally found during second inspection in RFV or in SFV were located in the transverse and left-sided colon and were>5 mm in size.CONCLUSION Second inspection of the whole colon leads to increased adenoma detection with no differences between SFV and RFV.Hence,increased detection is most likely a feature of the second inspection itself but not of the inspection mode.

Mechanistic Insight into Supramolecular Polymerization in Water Tunable by Molecular Geometry

Supramolecular self-assembly in water based on non-covalent bonding is attracting major attention due to the potential of hydrogels and aqueous polymers in biomedical applications.Although supramolecular polymerization in organic solvents is well established,the key design features,the assembly mechanisms in water and achieving control over the aggregate structures remain challenging.Here,we present the assembly and disassembly of geometrical isomers of a stiff-stilbene bis-urea amphiphile(SA)in pure water.A remarkable feature of this system is that the(E)-isomer forms supramolecular polymers in both pure water and organic solvents.Taking advantage of this unique property,the hydrophobic effect was studied by comparing the supramolecular assembly in both systems.The assembly process inwater follows an enthalpy-driven nucleation-elongation(cooperative)supramolecular polymerization mechanism with a standard Gibbs free energy(ΔG°=−53 kJ mol^(−1))double the value of the one found in toluene.We attributed this distinctive feature to the hydrophobic effect in water.Furthermore,we discovered an isomer-dependent assembly process,which can be used to control aggregation in aqueous media.Due to the substantial geometric difference between(E)-SA and(Z)-SA,we compared their assembly in water to study the influence of different driving forces involved in the process.The supramolecular polymerization of(E)-SA was cooperatively influenced by hydrogen bonding,π-stacking,and hydrophobic effects,whereas the assembly of(Z)-SAwasmainly driven by hydrophobic effects.As a result,the fiber length of(E)-SA in water is much longer than that of(Z)-SA,presenting opportunities for geometrical control of aggregation in aqueousmedia.