Manipulating Crystal Growth and Secondary Phase PbI_(2)to Enable Efficient and Stable Perovskite Solar Cells with Natural Additives

In perovskite solar cells(PSCs),the inherent defects of perovskite film and the random distribution of excess lead iodide(PbI_(2))prevent the improvement of efficiency and stability.Herein,natural cellulose is used as the raw material to design a series of cellulose derivatives for perovskite crystallization engineering.The cationic cellulose derivative C-Im-CN with cyano-imidazolium(Im-CN)cation and chloride anion prominently promotes the crystallization process,grain growth,and directional orientation of perovskite.Meanwhile,excess PbI_(2)is transferred to the surface of perovskite grains or formed plate-like crystallites in local domains.These effects result in suppressing defect formation,decreasing grain boundaries,enhancing carrier extraction,inhibiting non-radiative recombination,and dramatically prolonging carrier lifetimes.Thus,the PSCs exhibit a high power conversion efficiency of 24.71%.Moreover,C-Im-CN has multiple interaction sites and polymer skeleton,so the unencapsulated PSCs maintain above 91.3%of their initial efficiencies after 3000 h of continuous operation in a conventional air atmosphere and have good stability under high humidity conditions.The utilization of biopolymers with excellent structure-designability to manage the perovskite opens a state-of-the-art avenue for manufacturing and improving PSCs.

Eco-friendly fractionation of natural straws:sustainable ultralong room-temperature phosphorescence and super anti-ultraviolet materials

We demonstrate a new green solvent consisting of ionic liquid and polyol to achieve a selective fractionation of lignin from biomass.The lignin from corn straw is rich in syringyl unit and phenolic hydroxyl group,resulting in excellent room-temperature phosphorescence(RTP)performance,antioxidation property and long-term photostability.Flexible film,fiber,aerogel and coatings with an ultralong RTP lifetime of 0.654 s are obtained.The lignin from corn straw completely blocks UV light of290–400 nm at an extremely low usage due to many p-coumarate units.When the content is as low as 1.54 mg/g,which is two orders of magnitude lower than the previous reports,the corresponding sunscreen cream has a super-high sun protection factor(SPF)of 183.9.More importantly,the lignin self-assembles into nanospheres of 250–350 nm,preventing penetration into the skin.Such easily-available,abundant,low-cost,safe and natural lignin provides an innovative avenue for sustainable optical function materials.

Spontaneous,scalable,and self-similar superhydrophobic coatings for all-weather deicing

Herein,we proposed and demonstrated a facile and scalable strategy to fabricate multifunctional self-similar superhydrophobic coatings.Firstly,a hydrophobic cationic cellulose derivative containing imidazolium cation was synthesized by a controllable derivatization.It could effectively disperse one-dimensional(1D)multi-walled carbon nanotubes(MWCNT),because the imidazolium cations formed cation–πinteractions with MWCNT.Further,the synergy effect of the cationic cellulose derivative and MWCNT dispersed two-dimensional(2D)reduced graphene oxide(rGO)to obtain a three-components nano-dispersion.Finally,via a simple spaying process,a superhydrophobic coating with self-similar micro-nano structures spontaneously formed from inside to outside,owing to the various nanostructures with different shapes and sizes in the dispersion and the adhesive effect of the cellulose derivative.This superhydrophobic coating was easy to scale,exhibited superior stability owing to the renewal micro-nano structures.It retained the superhydrophobicity even if it was treated by rubbing for 1500 times.Moreover,it had outstanding photo-thermal and Joule-heating performance,because of the strong solar absorption and high electrical conductivity of MWCNT and rGO.It provided both passive anti-icing and active deicing effects.Thus,it could achieve all-weather anti-icing for wind power generators under sunlight and low voltage conditions.Such facile preparation method and multifunctional renewable superhydrophobic coating hold great application prospects.

Cellulose-Based Ultralong Room-Temperature Phosphorescence Nanomaterials with Tunable Color and High Quantum Yield via Nano-Surface Confining Effect

How to achieve multicolor organic room-temperature phosphorescence(RTP)is still challenging and striking.Herein,we discovered a new principle to construct eco-friendly color-tunable RTP nanomaterials based on the nano-surface confining effect.Cellulose nanocrystal(CNC)immobilized cellulose derivatives(CX)containing aromatic substituents via hydrogen-bonding interactions,which effectively inhibit the motion of cellulose chains and luminescent groups to suppress the nonradiative transitions.Meanwhile,CNC with a strong hydrogen-bonding network can isolate oxygen.CX with different aromatic substituents regulate the phosphorescent emission.After mixing CNC and CX directly,a series of polychromatic ultralong RTP nanomaterials were obtained.The RTP emission of the resultant CX@CNC can be finely adjusted through the introduction of various CX and the regulation of the CX/CNC ratio.Such a universal,facile,and effective strategy can be used to fabricate various colorful RTP materials with wide color gamut.Because of the complete biodegradability of cellulose,the multicolor phosphorescent CX@CNC nanomaterials can be used as eco-friendly security inks to fabricate disposable anticounterfeiting labels and information-storage patterns via conventional printing and writing processes.

Click Modification for Polysaccharides via Novel Tunnel Transmission Phenomenon in Ionic Liquids

It is extremely dificult toachievearapid and effcient modifcationofnatural polysaccharides,due tothe intrinsicstrong hydrogen bonding networks and the slow mass transfer process during the reaction process.Herein,we found a fascinating anion-tunnel transmission phenomenon in the imidazolium-based ionic liquids with carboxylate anions.A novel click esterification of natural polysaccharides thus was demonstrated undera catalyst-free condition within a very short reaction time of15min at O-80C.Such a super-rapid and highly eficient modification strategy is available for various polysaccharides(clluoe,starchinulin,pululan,dextranand xylan),difrentesterifcatonreactions(acetication,propionation benzoylation,and cyclohexylformylation),and high concentrations,claiming a revolutionary potential in polysaccharide chemistry industries.