Piperazine-Assisted Construction of 2D/3D Wide-Bandgap Perovskite for Realizing High-Efficiency Perovskite/Organic Tandem Solar Cells

Monolithic perovskite/organic tandem solar cells(TsCs)have gained significant attention due to their easy device integration and the potential to surpass the Shockley-Queisser limit of single-junction solar cells.However,the surfaces of wide-bandgap perovskite films are densely populated with defects,leading to severe non-radiative recombination and energy loss.As a consequence,the power conversion efficiency(PCE)of perovskite/organic TSCs lags behind that of other TSC counterparts.To address these issues,we designed a functional ammonium salt,4-(2-hydroxyethyl)piperazin-1-ium iodide(Pzol),comprising a piperazine iodide and a terminated hydroxyl group,which was applied for post-treating the perovskite surface.Our findings reveal that Pzol reacts with and consumes residual PbX_(2)(X:I or Br)to form a 2D perovskite component,thereby eliminating Pb^(0)defects,while the terminated hydroxyl group in PZOI can also passivate uncoordinated Pb^(2+).Consequently,the shallow/deep-level defect densities of the 2D/3D perovskite film were significantly reduced,leading to an enhanced PCE of single-junction 2D/3D wide-bandgap perovskite solar cells to 18.18% with a reduced energy loss of 40 mev.Importantly,the corresponding perovskite/organic TSCs achieved a remarkable PCE of 24.05% with enhanced operational stability(T_(90)~500h).

Frontiers in circularly polarized luminescence:molecular design,self-assembly,nanomaterials,and applications

The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.

Assembly Induced Super-Large Red-Shifted Absorption:The Burgeoning Field of Organic Near-Infrared Materials

Supramolecular assembly of organic dye compounds with J-aggregation leads to a red-shifted absorption spectrum that greatly facilitates the construction of near-infrared(NIR)materials.A considerable improvement of the material functions requires that the absorption red-shift be larger than 100 nm,but such a super-large red-shift is challenging,and the rules leading to the super-large red-shifted absorption is still not explicit.In this review,we focused on those J-aggregated organic dye materials with super-large red-shifted absorption.The nature of the super-large red-shift is originated fromthe intermolecular charge transfer between neighboring chromophores.The super-large red-shift can be obtained by tuning either the molecular structure or kinetic assembly process in a delicate manner.Materials with super-large red-shifted absorption have been successfully applied to biological imaging,phototherapy,electronic devices,and solar cells,and show great potential in many other fields.The elaboration of assembly induced super-large red-shifted absorption is promising for design of supramolecular NIR materials with tuned structures,enhanced functionalities,and a wide array of applications.

Viologen derivatives with extendedπ-conjugation structures:From supra-/molecular building blocks to organic porous materials

Recently,increasing atte ntion has been paid on extending theπ-conjugation structures ofviologens(1,1’-disubstituted-4,4’-bipyridylium salts)by incorporating planar aromatic units into the bipyridinium backbones.Various viologen derivative s with extendedπ-conjugation structures have been synthesized,including the N-termini aromatic substituted viologens,the extendedπ-conjugated viologens(denoted as ECVs)as well as theπ-conjugated oligomeric viologens(denoted as COVs).These compounds typically exhibit interesting properties distinguished from those of an isolated viologen unit,which make them as new class of electron deficient supra-/molecular building blocks in supramolecular chemistry and materials science.In this review,we would like to highlight the recent advances of viologen derivatives with extendedπ-conjugation structures in versatile applications ranging from electrochromic and energy storage materials,the ECV/COV-based supramolecular self-assembly systems including the linear supramolecular polymers and 2D/3D supramolecular organic frameworks(SOFs),to the viologen-based covalent organic frameworks(COFs)/networks.We hope this review will serve as an in-time summary worthy of referring,more importantly,to provide inspiration in the rational design of novel molecules with unexplored properties and functions.

Smart phosphorescence from solid to water through progressive assembly strategy based on dual phosphorescent sources

Developing smart room-temperature phosphorescence(RTP)materials with facile and efficient strategies have attracted increasing attention.Herein,tunable RTP materials with two phosphorescent sources and stepwise enhanced phosphorescence in water are obtained through an in-situ self-assembly strategy based on the sensitization of phosphors by trimesic acid(TMA)through simple doping and the rigidification of phosphors by hydrogen-bonded organic frameworks(HOFs).As expected,doped TMA+phosphors simultaneously promote the RTP emission of phosphors and maintain TMA phosphorescence.In-situ assembled HOF(MATMA)@phosphors facilitate smart RTP emission in water due to the coexistence of phosphorescent HOF(MA-TMA)host and phosphors guest.Additionally,such RTP materials with good processability demonstrate the application potential in information security,benefitting from their varied afterglow lifetimes and easy luminous recognition in the darkness.This work will inspire the design of dual phosphorescent source RTP systems and provide new strategies for the development of smart RTP materials in water.