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The bottom contact in perovskite solar cells (PSCs) is easy to cause deep trap states and severe instability issues, especially under maximum power point tracking (MPPT). In this study, sodium gluconate (SG) is employed to disperse tin oxide (SnO 2 ) nanoparticles (NPs) and regulate the interface contact at the buried interface. The SG-SnO 2 electron transfer layer (ETL) enabled the deposition of pinhole-free perovskite films in ambient air and improved interface contact by bridging effect. SG-SnO 2 PSCs achieved an impressive power conversion efficiency (PCE) of 25.34% (certified as 25.17%) with a high open-circuit voltage (V OC ) exceeding 1.19 V. The V OC loss is less than 0.34 V relative to the 1.53 eV bandgap, and the fill factor (FF) loss is only 2.02% due to the improved contact. The SG-SnO 2 PSCs retained around 90% of their initial PCEs after 1000 h operation (T 90 = 1000 h), higher than T 80 = 1000 h for the control SnO 2 PSC. Microstructure analysis revealed that light-induced degradation primarily occurred at the buried holes and grain boundaries and highlighted the importance of bottom-contact engineering., (© 2024 Wiley‐VCH GmbH.)

Producing heterostructures of cesium lead halide perovskites and metal-chalcogenides in the form of colloidal nanocrystals can improve their optical features and stability, and also govern the recombination of charge carriers. Herein, the synthesis of red-emitting CsPbI 3 /ZnSe nanoheterostructures is reported via an in situ hot injection method, which provides the crystallization conditions for both components, subsequently leading to heteroepitaxial growth. Steady-state absorption and photoluminescence studies alongside X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy analysis evidence on a type-I band alignment for CsPbI 3 /ZnSe nanoheterostructures, which exhibit photoluminescence quantum yield of 96% due to the effective passivation of surface defects, and an enhancement in carrier lifetime. Furthermore, the heterostructure growth of ZnSe domains leads to significant improvement in the stability of the CsPbI 3 nanocrystals under ambient conditions and against thermal and UV irradiation stress., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

The exploration of high-performance and low-cost wide-bandgap polymer donors remains critical to achieve high-efficiency nonfullerene organic solar cells (OSCs) beyond current thresholds. Herein, the 1,2,3-benzothiadiazole (iBT), which is an isomer of 2,1,3-benzothiadiazole (BT), is used to design wide-bandgap polymer donor PiBT. The PiBT-based solar cells reach efficiency of 19.0%, which is one of the highest efficiencies in binary OSCs. Systemic studies show that isomerization of BT to iBT can finely regulate the polymers' photoelectric properties including i) increasing the extinction coefficient and photon harvest, ii) downshifting the highest occupied molecular orbital energy levels, iii) improving the coplanarity of polymer backbones, iv) offering good thermodynamic miscibility with acceptors. Consequently, the PiBT:Y6 bulk heterojunction (BHJ) device simultaneously reaches advantageous nanoscale morphology, efficient exciton generation and dissociation, fast charge transportation, and suppressed charge recombination, leading to larger V OC of 0.87 V, higher J SC of 28.2 mA cm -2 , greater fill factor of 77.3%, and thus higher efficiency of 19.0%, while the analog-PBT-based OSCs reach efficiency of only 12.9%. Moreover, the key intermediate iBT can be easily afforded from industry chemicals via two-step procedure. Overall, this contribution highlights that iBT is a promising motif for designing high-performance polymer donors., (© 2024 Wiley‐VCH GmbH.)

Due to the fast dynamics and re-equilibration of supramolecular self-assembly, bottom-up molecular strategies to fabricate well-defined and controllable multiblock structures are rare. Herein, we propose a new concept for fabrication of fluorescent multiblock microcolumns containing 1 to 7 blocks via hierarchical supramolecular self-assembly based on cucurbit[8]uril (CB[8]), NaBr and an AIEgen guest. Through the complexation between CB[8] and different numbers of AIEgen guests (2, 1, 0), the competitive displacement caused by the binding of the sodium cation to the CB[8] portal, and the reversible assembly of positively charged guests in salt solutions, one-pot hierarchical supramolecular self-assembly is realized. The molecular structure of each block is analyzed by single-crystal X-ray diffraction. The AIEgen enables the self-assembly of multiblocks to be visualized, understood, and regulated., (© 2022 Wiley-VCH GmbH.)

Central π-core engineering of non-fullerene small molecule acceptors (NF-SMAs) is effective in boosting the performance of organic solar cells (OSCs). Especially, selenium (Se) functionalization of NF-SMAs is considered a promising strategy but the structure-performance relationship remains unclear. Here, we synthesize two isomeric alkylphenyl-substituted selenopheno[3,2-b]thiophene-based NF-SMAs named mPh4F-TS and mPh4F-ST with different substitution positions, and contrast them with the thieno[3,2-b]thiophene-based analogue, mPh4F-TT. When placing Se atoms at the outer positions of the π-core, mPh4F-TS shows the most red-shifted absorption and compact molecular stacking. The PM6 : mPh4F-TS devices exhibit excellent absorption, high charge carrier mobility, and reduced energy loss. Consequently, PM6 : mPh4F-TS achieves more balanced photovoltaic parameters and yields an efficiency of 18.05 %, which highlights that precisely manipulating selenium functionalization is a practicable way toward high-efficiency OSCs., (© 2022 Wiley-VCH GmbH.)

3D mixed-halide perovskite-based red emitters combine excellent charge-transport characteristics with simple solution processing and good film formation; however, light-emitting diodes (LEDs) based on these emitters cannot yet outperform their nanocrystal counterparts. Here the use of diammonium halides in regulating the formation of mixed bromide-iodide perovskite films is explored. It is found that the diammonium cations preferentially bond to Pb-Br, rather than Pb-I, octahedra, promoting the formation of quasi-2D phases. It is proposed that the perovskite formation is initially dominated by the crystallization of the thermodynamically more favorable 3D phase, but, as the solution gets depleted from the regular A cations, thin shells of amorphous quasi-2D perovskites form. This leads to crystalline perovskite grains with efficiently passivated surfaces and reduced lattice strain. As a result, the diammonium-treated perovskite LEDs demonstrate a record luminance (10745 cd m -2 ) and half-lifetime among 3D perovskite-based red LEDs., (© 2022 Wiley-VCH GmbH.)

Integrating highly efficient photovoltaic (PV) function into light-emitting diodes (LEDs) for multifunctional display is of great significance for compact low-power electronics, but it remains challenging. Herein, it is demonstrated that solution engineered perovskite nanocrystals (PNCs, ≈100 nm) enable efficient electroluminescence (EL) and PV performance within a single device through tailoring the dispersity and interface. It delivers the maximum brightness of 490 W sr -1  m -2 at 2.7 V and 23.2% EL external quantum efficiency, a record value for near-infrared perovskite LED, as well as 15.23% PV efficiency, among the highest value for nanocrystal perovskite solar cells. The PV-EL performance is well in line with the reciprocity relation. These all-solution-processed PV-LED devices open up viable routes to a variety of advanced applications, from touchless interactive screens to energy harvesting displays and data communication., (© 2022 Wiley-VCH GmbH.)

Integration of photovoltaic (PV) and electroluminescent (EL) functions and/or units in one device is attractive for new generation optoelectronic devices but it is challenging to achieve highly comprehensive efficiency. Herein, perovskite solar cells (PSCs) are fabricated, assisted by 3-sulfopropyl methacrylate potassium salt (SPM) additive to tackle this issue. SPMs not only induce large grain size during the film formation but also produce a secondary phase of 2D K 2 PbI 4 to passivate the grain boundaries (GBs). In addition, its sulfonic acid group and potassium ion can coordinate to lead ion and fill the interstitial defects, respectively. Thus, SPM reduces the defective states and suppresses nonradiative recombination loss. As a result, planar PSC delivers a power conversion efficiency of ≈22%, with a maximum open-circuit voltage (V oc ) of 1.20 V. The V oc is 94% of the radiative V oc limit (1.28 V), higher than the control device (V oc of 1.12 V). In addition, the reciprocity between PV and EL is also correlated to quantify the energy losses and understand the device physics. When operated as a light-emitting diode, the maximum EL external quantum efficiency (EQE EL ) is up to 12.2% (EQE EL of 10.7% under an injection current of short-circuit photocurrent), thus leading to high-performance PV/EL dual functions., (© 2021 Wiley-VCH GmbH.)

While there has been extensive investigation into modulating quasi-2D perovskite compositions in light-emitting diodes (LEDs) for promoting their electroluminescence, very few reports have studied approaches involving enhancement of the energy transfer between quasi-2D perovskite layers of the film, which plays very important role for achieving high-performance perovskite LEDs (PeLEDs). In this work, a bifunctional ligand of 4-(2-aminoethyl)benzoic acid (ABA) cation is strategically introduced into the perovskite to diminish the weak van der Waals gap between individual perovskite layers for promoting coupled quasi-2D perovskite layers. In particular, the strengthened interaction between coupled quasi-2D perovskite layers favors an efficient energy transfer in the perovskite films. The introduced ABA can also simultaneously passivate the perovskite defects by reducing metallic Pb for less nonradiative recombination loss. Benefiting from the advanced properties of ABA incorporated perovskites, highly efficient blue PeLEDs with external quantum efficiency of 10.11% and a very long operational stability of 81.3 min, among the best performing blue quasi-2D PeLEDs, are achieved. Consequently, this work contributes an effective approach for high-performance and stable blue PeLEDs toward practical applications., (© 2020 Wiley-VCH GmbH.)

The traditional design strategies for highly bright solid-state luminescent materials rely on weakening the intermolecular π-π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid-state fluorescence. TBP-e-TPA with a molecular rotor in the end position of a planar core adopts a long-range cofacial packing mode, which in the solid state is almost non-emissive. By shifting molecular rotors to the bay position, the resultant TBP-b-TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid-state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP-b-TPA nanoparticles were used for two-photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid-state fluorophores., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Because of their innate ability to store and then release energy, long-persistent luminescence (LPL) materials have garnered strong research interest in a wide range of multidisciplinary fields, such as biomedical sciences, theranostics, and photonic devices. Although many inorganic LPL systems with afterglow durations of up to hours and days have been reported, organic systems have had difficulties reaching similar timescales. In this work, a design principle based on the successes of inorganic systems to produce an organic LPL (OLPL) system through the use of a strong organic electron trap is proposed. The resulting system generates detectable afterglow for up to 7 h, significantly longer than any other reported OLPL system. The design strategy demonstrates an easy methodology to develop organic long-persistent phosphors, opening the door to new OLPL materials., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Currently, photovoltaic/electroluminescent (PV/EL) perovskite bifunctional devices (PBDs) exhibit poor performance due to defects and interfacial misalignment of the energy band. Interfacial energy-band engineering between the perovskite and hole-transport layer (HTL) is introduced to reduce energy loss, through adding corrosion-free 3,3'-(2,7-dibromo-9H-fluorene-9,9-diyl) bis(n,n-dimethylpropan-1-amine) (FN-Br) into a HTL free of lithium salt. This strategy can turn the n-type surface of perovskite into p-type and thus correct the misalignment to form a well-defined N-I-P heterojunction. The tailored PBD achieves a high PV efficiency of up to 21.54% (certified 20.24%) and 4.3% EL external quantum efficiency. Free of destructive additives, the unencapsulated devices maintain >92% of their initial PV performance for 500 h at maximum power point under standard air mass 1.5G illumination. This strategy can serve as a general guideline to enhance PV and EL performance of perovskite devices while ensuring excellent stability., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Circularly-polarized luminescence (CPL) has received new attention on the rise of applications to generate devices and biologically active probes. These applications require fluorophores that are not only chiral but also provide strong fluorescence intensity in aggregated state. Thus, a new research branch has opened up a few years ago, which allows CPL-active fluorophores to be emissive in aggregated-state. As a result, reports on the combination of the CPL property with the aggregation-induced emission (AIE) phenomenon have emerged. Herein the early design principles that have been reported until now to generate CPL-active AIE-active fluorophores (AIEgens) are summarized. In this regard the alignment of monomeric emitters in a chiral fashion, either in supramolecules, polymers or liquid crystals has been proven to be a successful approach. Additionally, first reports have appeared that demonstrate how to tackle the daunting task to furnish individual CPL-active AIEgens., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

By introducing chiral leucine pendants to silole scaffold, leucine-containing silole (Silole-Leu) is synthesized and it is endowed with not only aggregation-induced emission and circular dichroism, but excellent chiral polarized luminescence as well. Silole-Leu also has the capacity to self-assemble into nano/micro helical luminescent fibers and the dimension of the fibers can be tuned by adjusting the ratio and volume of mixed solvents for evaporation as revealed by atomic force microscope, scanning electron microscope, and fluorescence microscope. The characteristic helicity of microfibers is directly visualized for the first time by using fluorescence microscope., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of newly synthesized dicyanoplatinum(II) 2,2'-bipyridine complexes exhibits self-assembly properties in solution after the incorporation of the l-valine amino units appended with various hydrophobic motifs. These l-valine-derived substituents were found to have critical control over the aggregation behaviors of the complexes in the solution state. On one hand, one of the complexes was found to exhibit interesting circularly polarized luminescence (CPL) signals at low temperature due to the formation of chiral spherical aggregates in the temperature-dependent studies. On the other hand, systematic transformation from less uniform aggregates to well-defined fibrous and rod-like structures via Pt⋅⋅⋅Pt and π-π stacking interactions has also been observed in the mixed-solvent studies. These changes were monitored by UV/Vis absorption, emission, circular dichroism (CD), and CPL spectroscopies, and morphologies were studied by electron microscopy., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A polymer/PCBM hybrid electron transport layer is reported that enables high-performance perovskite solar cells with a high power conversion efficiency of 16.2% and with negligible hysteresis. Unlike previous approaches of reducing hysteresis by thermal annealing or fullerene passivation, the success of our approach can be mainly attributed to the doping of the PCBM layer using an insulating polymer (polystyrene) and an amine-containing polymeric semiconductor named PFNOX.

We present a nitrogen-containing polycyclic aromatic hydrocarbon (N-PAH), namely 12-methoxy-9-(4-methoxyphenyl)-5,8-diphenyl-4-(pyridin-4-yl)pyreno[1,10,9-h,i,j]isoquinoline (c-TPE-ON), which exhibits high quantum-yield emission both in solution (blue) and in the solid state (yellow). This molecule was unexpectedly obtained by a three-fold, highly regioselective photocyclodehydrogenation of a tetraphenylethylene-derived AIEgen. Based on manifold approaches involving UV/Vis, photoluminescence, and NMR spectroscopy as well as HRMS, we propose a reasonable mechanism for the formation of the disk-like N-PAH that is supported by density functional theory calculations. In contrast to most PAHs that are commonly used, our system does not suffer from entire fluorescence quenching in the solid state due to the peripheral aromatic rings preventing π-π stacking interactions, as evidenced by single-crystal X-ray analysis. Moreover, its rod-like microcrystals exhibit excellent optical waveguide properties. Hence, c-TPE-ON comprises a N-PAH with unprecedented luminescent properties and as such is a promising candidate for fabricating organic optoelectronic devices. Our design and synthetic strategy might lead to a more general approach to the preparation of solution- and solid-state luminescent PAHs., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel mitochondrion-specific live-cell fluorescence turn-on photoactivatable bioprobe, named o-TPP3M, is designed and readily prepared, operating in a new photoactivatable mechanism based on a twisted intramolecular charge-transfer effect, the restriction of intramolecular rotations, and photocyclodehydrogenation. This bioprobe exhibits unique photoactivation behavior, a large signal-to-background ratio, and no cytotoxicity to living cells, providing a promising candidate for varied bioresearch., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this paper, a simple strategy to change the emission behaviour of luminogenic materials was developed. Tetraphenylethene (TPE)-functionalised benzothiazolium salts with different counteranions (TPEBe-X; X=I(-), ClO(4)(-) and PF(6)(-)) were designed and synthesised. All the luminogens show weak red emission in the solution state that originates from intramolecular charge transfer from TPE to the benzothiazolium unit. Whereas aggregate formation enhances the light emission of TPEBe-ClO(4) and TPEBe-PF(6), that of TPEBe-I is quenched, thus demonstrating the phenomena of aggregation-induced emission and aggregation-caused quenching. TPEBe-I works as a light-up fluorescent sensor for Hg(2+) in aqueous solution with high sensitivity and specificity owing to the elimination of the emission quenching effect of the iodide ion by the formation of HgI(2) as well as the induction in aggregate formation by the complexation of Hg(2+) with the S atom of the benzothiazolium unit of TPEBe-I. A solid film of TPEBe-I was prepared that can monitor the level of Hg(2+) in aqueous solution with a detection limit of 1 μM.

Amplified spontaneous emission under millisecond pulsed excitation on a rotaxane-insulated conjugated polymer is reported. Pump-probe spectroscopy confirms the absence of polaron-pair absorption in the gain spectral region as the main factor contributing to quasi-steady-state amplified spontaneous emission. The low polaron-pair yield in this compound is the likely result of effective backbone encapsulation provided by the threading ring., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stereoregular tetraphenylethene derivatives (Z)-o-BCaPTPE and (Z)-o-BTPATPE featured with chiasmatic conformations and aggregation-enhanced emission characteristics are synthesized using a McMurry reaction. Both luminogens exhibit high hole and electron mobilities. Organic light-emitting diodes (OLEDs) using (Z)-o-BCaPTPE and (Z)-o-BTPATPE as both the light-emitting and electron-transporting layers show high efficiencies., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A silicon-containing hyperbranched polymer (hb-P1/2) with σ*-π* conjugation was prepared in a good yield and high molecular weight by rhodium-catalyzed alkyne polyhydrosilylation of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene (1) with tris(4-dimethylsilylphenyl)amine (2). The polymer was thermally stable, losing merely 5% of its weight when heated to ≈445 °C. Whereas hb-P1/2 was weakly luminescent when molecularly dissolved, it became highly emissive when supramolecularly aggregated, showing an aggregation-induced emission (AIE) phenomenon. A superamplification effect was observed when the AIE nanoaggregates were used as fluorescent chemosensor for explosive detection: the quenching efficiency was greatly increased in a nonlinear fashion with increasing quencher concentration., (Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Whereas most conventional DNA probes are flat disklike aromatic molecules, we explored the possibility of developing quadruplex sensors with nonplanar conformations, in particular, the propeller-shaped tetraphenylethene (TPE) salts with aggregation-induced emission (AIE) characteristics. 1,1,2,2-Tetrakis[4-(2-triethylammonioethoxy)phenyl]ethene tetrabromide (TPE-1) was found to show a specific affinity to a particular quadruplex structure formed by a human telomeric DNA strand in the presence of K(+) ions, as indicated by the enhanced and bathochromically shifted emission of the AIE fluorogen. Steady-state and time-resolved spectral analyses revealed that the specific binding stems from a structural matching between the AIE fluorogen and the DNA strand in the folding process. Computational modeling suggests that the AIE molecule docks on the grooves of the quadruplex surface with the aid of electrostatic attraction. The binding preference of TPE-1 enables it to serve as a bioprobe for direct monitoring of cation-driven conformational transitions between the quadruplexes of various conformations, a job unachievable by the traditional G-quadruplex biosensors. Methyl thiazolyl tetrazolium (MTT) assays reveal that TPE-1 is cytocompatible, posing no toxicity to living cells.