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The hole transport materials that interact with the indium tin oxide (ITO) surface can be processed into monomolecular layers (MLs), which often exhibit different surface and electronic properties than their thin‐film counterparts. Herein, it is found that poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA) films (R‐PTAA) can be easily processed into ML (M‐PTAA) due to the van der Waals interaction between ITO and PTAA. However, compared with R‐PTAA, the work function (WF) and conductivity of M‐PTAA are simultaneously reduced by the charge transfer at the ITO/PTAA interface. To address this issue, a modified monomolecular layer strategy (m‐MLS) is developed, where a small amount of 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) is introduced to enhance the interaction force between ITO and PTAA. PTAA treated by m‐MLS (F‐PTAA) has a hydrophilic physical surface, closely matching electronic energy level with the perovskite layer and smaller bulk resistance. As a result, the efficiency and reproducibility of perovskite solar cells (PSCs) are substantially improved. PSCs based on F‐PTAA demonstrated the highest power conversion efficiency (PCE) of 19.7% with a fill factor of over 80%. This study inspires the development of novel interface modification materials, and provides a simple and convenient direction for the fabrication of high‐performance and reproducible inverted PSCs with high fill factors. [ABSTRACT FROM AUTHOR]

Hole transport materials and their processing occupy at least one‐third of the cost of perovskite solar cells (PSCs), which leaves plenty of room to improve the process of device fabrication. Herein, a facile immersing and washing strategy (I‐method) is reported to prepare effective organic monomolecular layers (MLs) of poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl) benzidine] (polyTPD) as hole transport layers (ML‐HTLs) to construct cost‐effective planar inverted PSCs. The ML enables an enhanced wettability to perovskite precursors and thus results in the growth of compact and uniform perovskite films. In addition, the ML exhibits better energy‐level alignment with perovskite. Consequently, the ML‐polyTPD‐based PSCs deliver significantly enhanced power conversion efficiency (PCE) and reproducibility, as compared to that of pristine polyTPD based devices. The practical consumption of polyTPD during the I‐method is cut to the bone, with the cost of $0.8 for 1 m2 substrate being achieved, which is 0.15% of that by S‐method. The developed I‐method is facile, and time‐ and cost‐saving with low requirement for facilities as well as with low temperature and solution processability. This strategy is cost‐effective to prepare ML‐HTLs for large‐area and flexible PSCs with competitive photovoltaic performance and enhanced reproducibility. [ABSTRACT FROM AUTHOR]

For the commercialization of perovskite solar cells (PSCs), it is more appealing to develop high‐performance simplified PSCs where perovskite films are just sandwiched between the back and front electrodes, in order to simplify the fabrication process and to reduce the cost. However, to date, this kind of devices shows rather low performance, and there are few researches on this subject. Herein, we report on a kind of compact PSCs (CPSCs) that are free of independent charge transport layers (CTLs). The devices are realized by the use of organic monolayer‐modified effective electrodes, along with the use of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM)‐assisted anti‐solvent technique to obtain ultra‐thin (~10 nm) PCBM‐embedded perovskite films. Compared to control devices, CPSCs achieve a promising champion power conversion efficiency of 19.6% with largely reduced hysteresis. Moreover, the unencapsulated CPSC shows good stability under ambient atmosphere, with only 10% efficiency loss after 60 days' storage. This work indicates that, by delicate design, CPSCs with smaller materials consumption in device architecture can perform competitively as conventional PSCs. Further reduction in the actual usage of costly CTL materials can be expected upon our CPSCs by developing more facile and economic methods to prepare ultra‐thin CTLs. [ABSTRACT FROM AUTHOR]

MXenes and doped carbon nanotubes (CNTs) have entered into research arenas for high‐rate energy storage and conversion. Herein, a method of postsynthesis of MXenes in boron, nitrogen codoped CNTs (BNCNTs) is reported with their electrocatalytical hydrogen evolution performance. The encapsulation of hexagonal molybdenum nitrate nanoparticles (h‐MoN NPs) into BNCNTs protects h‐MoN NPs from agglomeration and poisoning in the complex environment. In principle, the synergism of B and N dopants on the doped CNTs and confined h‐MoN NPs produces extremely active sites for electrochemical hydrogen evolution. Density functional theory calculations reveal that the active sites for hydrogen evolution originate from the synergistic effect of h‐MoN(001)/CN (graphitic N doping) and h‐MoN(001)/BNC. The h‐MoN@BNCNT electrocatalyst exhibits a small overpotential of 78 mV at 10 mA cm−2 and Tafel slope of 46 mV per decade, which are dramatically improved over all reported MoN‐based materials and doped CNTs. Additionally, it also exhibits outstanding electrochemical stability in environments with various pH values and seawater media from South China Sea.Nanoflakes of hexagonal molybdenum nitrate are synthesized in the matrix of boron, nitrogen codoped carbon nanotubes with efficient electrocatalytic hydrogen evolution performance in acidic, neutral, and alkaline solutions. Electrolysis of seawater can also be operated by using as‐obtained catalysts because doped carbon nanotubes can protect hexagonal molybdenum nitrate from agglomeration and poisoning in the complex environment. [ABSTRACT FROM AUTHOR]

Abstract: A Lewis‐acid promoted chemoselective condensation of 2‐aminobenzimidazoles or 3‐aminoindazoles with 3‐ethoxycyclobutanones is presented. Diverse fused heterocycles benzo[4,5]‐imidazo[1,2‐a]pyrimidine and pyrimido[1,2‐b]‐indazole derivatives were obtained in moderate to high yields under mild conditions, the reaction mechanism of which was in sharp contrast to previous [3+3] annulation reaction of 3‐ethoxycyclobutanones. [ABSTRACT FROM AUTHOR]

In article number 1805893, Zikang Tang, Chun Cheng, and co‐workers report a method of synthesis of carbon nanotube‐based nanocomposites. MXene nanoflakes, hexagonal molybdenum nitrides, are introduced into a boron, nitrogen co‐doped carbon nanotube matrix by pyrolysis of polyoxometalates and urotropine. The growth of MXenes is induced by urotropine while the carbon nanotube matrixes confine the overgrowth of the nanoflakes. The nanocomposite exhibits outstanding electrocatalytical performance for hydrogen production from seawater. [ABSTRACT FROM AUTHOR]

In article no. 1800173, Baomin Xu and Chun Cheng describe an effective strategy for introducing a polymer‐assisted small molecule layer as a hole transport layer to develop highly efficient inverted perovskite solar cells, in which the champion device exhibits a power conversion efficiency of >21%. A much smoother surface for the mixed hole transport layer and largely reduced charge recombination is obtained, and the energy level alignment is more matched with that of the perovskite. [ABSTRACT FROM AUTHOR]