Organic emitters play a vital role in determining the overall performance of organic light emitting diode (OLED) devices. Traditional fluorescent emitters can only achieve external quantum efficiency (EQE) of 5%, far below expectation; therefore many efforts have been spent on increasing the EQE of OLEDs. Phosphorescence, thermally activated delayed fluorescence, triplet–triplet annihilation, and hybridized local and charge transfer are the most widely applied approaches to harvest the 75% triplet excitons for luminescence. As for selecting or designing suitable emitters for practical applications, it is strongly demanded to have an overall view about emitters of high exciton utilizing efficiency (EUE) from molecule level, i.e., the four common approaches mentioned above and some latest ones of the doublet, singlet fission, triplet–polar annihilation, and rotationally accessed spin state inversion, and also from the aggregated state such as aggregation‐induced emission. In this review, the current progress of highly efficient emitters is presented, covering the chemical structures, the high‐EUE mechanisms in molecule level and aggregated state, and their applications in OLED devices. This review hopefully will illustrate highly efficient electroluminescent materials and their mechanisms, but more importantly, provide helpful information on how to design or select suitable emitters for specific OLED devices.

Benzothiazole (BTA) belongs to the heterocyclic class of bicyclic compounds. BTA derivatives possesses broad spectrum biological activities such as anticancer, antioxidant, anti-inflammatory, anti-tumour, antiviral, antibacterial, anti-proliferative, anti-diabetic, anti-convulsant, analgesic, anti-tubercular, antimalarial, anti-leishmanial, anti-histaminic and anti-fungal among others. The BTA scaffolds showed a crucial role in the inhibition of the metalloenzyme carbonic anhydrase (CA). In this review an extensive literature survey over the last decade discloses the role of BTA derivatives mainly as anticancer agents. Such compounds are effective against various types of cancer cell lines through a multitude of mechanisms, some of which are poorly studied or understood. The inhibition of tumour associated CAs by BTA derivatives is on the other hand better investigated and such compounds may serve as anticancer leads for the development of agents effective against hypoxic tumours. ARTICLE HISTORY

MXenes present unique features as materials for energy storage; however, limited interlayer distance, and structural stability with ongoing cycling limit their applications. Here, we have developed a unique method involving incorporating Nb atoms into MXene (Ti 3 C 2 ) to enhance its ability to achieve higher ionic storage and longer stability. Computational analysis using density functional theory was performed that explained the material structure, electronic structure, band structure, and density of states in atomistic detail. Nb-doped MXene showed a good charge storage capacity of 442.7 F/g, which makes it applicable in a supercapacitor. X-ray diffraction (XRD) indicated c-lattice parameter enhancement after Nb-doping in MXene (from 19.2A • to 23.4A • ), which showed the effect of the introduction of an element with a larger ionic radius (Nb). Also, the bandgap changes from 0.9 eV for pristine MXene to 0.1 eV for Nb-doped MXene, which indicates that the latter has the signature of increased conductivity due to more metallic nature, in support of the experimental results. This work presents not only the effect of doping in MXene but also helps to explain the phenomena involved in changes in physical parameters, advancing the field of energy storage based on 2D materials.

are covalently bonded and their unique characteristics enable them to demonstrate special performance in applications and distinguish them from other conventional organic salts. [12][13][14] Recently, a significant attention has been paid to the use of zwitterions owing to their solubility in polar solvents for solution processing, [15][16][17] and dipole formation for the transfer of carriers [18][19][20] and ions. [21][22][23] Zwitterions have emerged as alternatives to the widely used building blocks such as conventional ionic groups, for developing new functional materials. The presence of both negative and positive ions in the same molecule enables zwitterions to develop interfacial dipole. The ability of zwitterions to develop interfacial dipole provides a new pathway to utilize them as interfacial layer in optoelectronic devices, including organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting devices (OLEDs), as well as electrolyte additives for energy devices such as lithium ion batteries (LIBs).It is well known that the ability to transport the charge carriers between the electrodes and organic layers is very crucial to obtain highly efficient electronic devices. [24] A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers. [25] To get rid of this obstacle, an interlayer between the electrodes and organic layers is applied to facilitate the transfer of charges in organic devices. In OLEDs, interlayers are used to enhance charge injection and reduce the height of Schottky barrier. While in the case of OSCs and PVSCs, apart from the enhancement in charge injection, they also play an important role to increase the built-in electric field across the active layer, ensuring efficient extraction of photogenerated charge carriers. [26][27][28][29][30] Therefore, the design and development of effective interlayer materials for interfacial modification are crucial for high-performance electronic devices. Recently, some significant advances have been demonstrated by applying an interfacial layer between the electrodes and organic layers, resulting in power conversion efficiencies (PCEs) to exceed 14% for single-junction OSCs by choosing appropriate photoactive layer. [31,32] Among different interlayer materials used so far, zwitterionic materials have been proved Zwitterions, a class of materials that contain covalently bonded cations and anions, have been extensively studied in the past decades owing to their special features, such as excellent solubility in polar solvents, for solution processing and dipole formation for the transfer of carriers and ions. Recently, zwitterions have been developed as electrode modifiers for organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting devices (OLEDs), as well as electrolyte additives for lithium ion batteries (LIBs).With the rapid advances of zwitterionic materials, high-performan...

Abstract

The research on organic solar cells (OSCs) has made an immense progress over the last one decade because OSCs possess multiple advantages, such as light-weight, efficient, economical and large-area fabrication. [1][2][3] To date, the power conversion efficiency (PCE) at the laboratory scale has reached up to ≈16% by employing novel interfacial and photoactive materials. [4] Prior to the importance of photoactive layer, interfacial layer also plays a vital role to fabricate high-performance OSC by reducing the energy barrier at the interface and improving charge transfer. [5,6] However, it is usually impossible for the conventional single interlayer materials to satisfy all the requirements. In this regard, it is highly desirable to develop novel interfacial materials with suitable modification for highly efficient OSCs.To develop effective cathode interfacial materials, interface barrier should be minimized with improved electron mobility. Generally, interface barrier originates directly from the mismatch of the energy levels between the active layer and electrodes. Therefore, the key is to design suitable interfacial materials which can significantly reduce the interface barrier between the electrodes and active layer. In the past decades, numerous attempts have been made and significant progresses have been achieved for the cathode interface modification of OSCs. For example, few metallic salts, including LiF, CsF, and Cs 2 CO 3 , [7][8][9] have been integrated into OSCs to modify the interface and the devices exhibited enhanced efficiencies. However, the electron transfer ability of these metallic salts is low and these layers are thickness sensitive (<1 nm), which restrict their application on large scale. In this regard, some organic materials are also introduced for the interface modification of OSCs. Generally, organic materials are synthesized easily with high electron mobility and tunable bandgap energy. Some of them (poly [(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyfluorene)], polyethylenimine, and polyethylenimine ethoxylated (PEIE)) were found to be effective interface modifiers with matched performance of these devices, compared to the devices using conventional interlayer materials (Ca/Mg). [10,11] However, OSC devices. However, the limited resources, high-cost, and non-ecofriendly nature of petrochemical-based interface materials restrict their commercial applications. Here, a facile and effective approach to prepare cellulose and its derivatives as a cathode interface layer for OSCs with enhanced performance from rice straw of agroforestry residues is demonstrated. By employing this carboxymethyl cellulose sodium (CMC) into OSCs, a highly efficient inverted OSC is constructed, and a power conversion efficiency (PCE) of 12.01% is realized using poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-thiophen-2-yl)-benzo[1,2-b:4,5-b′] dithiophene))-alt-(5,5-(1′,3′-di-2thienyl-5′,7-bis(2-ethylhexyl)benzo[1′,2′-c: 4′,5′-c′]dithiophene-4,8-dione): 3,9-bis(2-methylene -((3-(1, 1-dicyanomethylen...

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The development of simple and water-/alcohol-soluble interfacial materials is crucial for the cost-effective fabrication process of polymer solar cells (PSCs). Herein, highly efficient PSCs are reported employing water-/alcohol-soluble and low-cost rhodamines as cathode interfacial layers (CILs). The results reveal that rhodamine-based CILs can reduce the work function of the Al cathode and simultaneously increase the open-circuit voltage, current density, fill factor, and power conversion efficiency (PCE) of PSCs. The solution-processed rhodamine-based PSCs demonstrated a remarkable PCE of 10.39%, which is one of the best efficiencies reported for thieno[3,4-b]thiophene/benzodithiophene:[6,6]-phenyl C-butyric acid methyl ester-based PSCs so far. The efficiency is also 42.3% higher than that of the vacuum-deposited Ca-based device (PCE of 7.30%) and 21.5% higher than that of the complicated solution-processable polymeric electrolyte poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)]-based device (PCE of 8.55%). Notably, rhodamines are very economical and have been extensively used as dyes in industries. Our work indicates that rhodamines have shown a strong potential as CILs compared to their counterparts in the large-area fabrication process of PSCs.