Among the above methods, the most common strategy is the one-step spincoating deposition assisted by an antisolvent, which is an easy and efficient approach to obtain dense and highly crystalline perovskite thin film. Three organic solvents-chlorobenzene (CB), [4b] methylbenzene (toluene), [4a] and diethyl ether (ether) [4c] -are the favorite antisolvents for this method. Efficient PSCs with PCE over 20% have been frequently obtained by using these antisolvents, [6] through the one-step spin-coating method.Three dominant parameters related to the one-step spin-coating process are: 1) the ratio between dimethylformamide (DMF):dimethyl sulfoxide (DMSO) in the perovskite precursor solution, 2) the antisolvent dripping time during the spin procedure, and 3) the antisolvent volume used for each coating process as depicted in Figure 1a. However, the current antisolvents mentioned above usually have very narrow and various operating windows. For instance, from the point of view of DMF/DMSO ratio, the proper value for CB is 4:1, [7] toluene is 7:3, [4a] while ether is 9:1. [4c] Meanwhile, the dripped antisolvent volume for each antisolvent is also different from case to case: 0.1 mL for CB, 0.5-1.0 mL for toluene, and 0.5 mL for ether. [4a,c,6a,7] This actuality means that only skillful experimenters can handle the spin-coating tricks and thus fabricate PCEs with high efficiency, which limits the development of the PSCs.Herein, we would like to introduce anisole as an antisolvent, with ultrawide processing window for the one-step fabrication of efficient and large-area PSCs. Using the anisole as antisolvent, there is no need to make any significant effort to obtain optimized conditions for the fabrication of high-quality perovskite films (Figure 1b). By dripping anisole on the spinning perovskite precursor film, it is possible to make dense and crystalline perovskite films as shown in Figure 1c,d. The thickness of the perovskite capping layer is about 450 nm, which is comparable with the perovskite thin films using the other antisolvents with optimized condition. [7,8] Also, the PCEs of PSCs fabricated using anisole are not sensitive to the precursor solution composition and antisolvent dripping parameters. We prepared perovskite thin films Photovoltaic technologies based on perovskite absorber materials have led this optoelectronic field into a brand-new horizon. However, the present antisolvents used in the one-step spin-coating method always encounter problems with the very narrow process window. Herein, anisole is introduced into the one-step spin-coating method, and the technology is developed to fabricate perovskite thin films with ultrawide processing window with a dimethylformamide (DMF):dimethyl sulfoxide (DMSO) ratio varying from 6:4 to 9:1 in the precursor solution, anisole dripping time ranging from 5 to 25 s, and an antisolvent volume varying from 0.1 to 0.9 mL. Perovskite thin films as large as 100 cm 2 are successfully fabricated using this method. Maximum photoelectric conversion efficiencies of 1...

Hybrid organic–inorganic halide perovskites (HPs) have garnered significant attention for use in resistive switching (RS) memory devices due to their low cost, low operation voltage, high on/off ratio, and excellent mechanical properties. However, the HP-based RS memory devices continue to face several challenges owing to the short endurance and stability of the HP film. Herein, two-dimensional/three-dimensional (2D/3D) perovskite heterojunction films were prepared via a low-temperature all-solution process and their RS behavior was investigated for the first time. The 2D/3D perovskite RS devices exhibited excellent performance with an endurance of 2700 cycles, a high on/off ratio of 106, and an operation speed of 640 μs. The calculated thermally assisted ion hopping activation energy and the results of the time-of-flight secondary ion mass spectroscopy demonstrated that the 2D perovskite layer could efficiently prevent the Ag ion migration into the 3D perovskite film. Moreover, we found that owing to its high thermal conductivity, the 2D perovskite can control the rupture of the Ag conductive filament. Thus, the 2D perovskite layer enhances endurance by controlling both Ag migration and filament rupture. Hence, this study provides an alternate strategy for improving endurance of HP-based RS memory devices.

In general, the quantum yields (QYs) of monolayer transition metal dichalcogenides (1L-TMDs) are low, typically less than 1% in their pristine state, significantly limiting their photonic applications. Many methods have been reported to increase the QYs of 1L-TMDs; however, the technical difficulties involved in the reliable estimation of these QYs have prevented the general assessment of these methods. Herein, we demonstrate the estimation of the QYs of 1L-TMDs using a poly methyl methacrylate (PMMA) thin film embedded with rhodamine 6G (R6G) as a reference specimen for measuring the QYs of 1L-TMDs. The PMMA/R6G composite films with thicknesses of 80 and 300 nm demonstrated spatially homogeneous emissions with the incorporation of well-dispersed R6G molecules, and may, therefore, be used as ideal reference specimens for the QY measurement of 1L-TMDs. Using our reference specimens, for which the QY ranged from 5.4% to 22.2% depending on the film thickness and R6G concentrations, we measured the QYs of the exfoliated or chemical vapor deposition (CVD)-grown 1L-WS2, -MoSe2, -MoS2, and -WSe2 TMDs. The convenient procedure proposed in this study for preparing the thin reference films and the simple protocol for the QY estimation of 1L-TMDs may enable accurate comparisons of the absolute QYs between the 1L-TMD samples, thereby enabling the development of a method to improve the QY of 1L-TMDs.

A high‐quality electron transport layer (ETL) is a critical component for the realization of high‐efficiency perovskite solar cells. We developed a controllable direct‐contact reaction process to prepare a chlorinated SnO2 (SnO2‐Cl) ETL. It is unique in that (a) 1′2‐dichlorobenzene is used to provide more reactive Cl radicals for more in‐depth passivation; (b) it does not introduce any impurities other than chlorine. It is found that the chlorine modification significantly improves the electron extraction. Consequently, its associated solar cell efficiency is increased from 17.01% to 17.81% comparing to the pristine SnO2 ETL without the modification. The hysteresis index is significantly reduced to 0.017 for the SnO2‐Cl ETL.

With skyrocketing interest and achievement of tremendous research efforts, perovskite solar cells are on the verge of commercialization. However, the stabilities of precursors and devices provide challenges for commercialization. Many researchers have dealt with these issues separately. Here, we introduce novel diphthalic anhydride-based Lewis base additives that address the precursor and device stability difficulties simultaneously. The added Lewis bases showed excellent interactions with Pb2+ and FA+ cations in the precursor and perovskite crystal. Accordingly, the facile Lewis-base-added perovskite precursor exhibited 85% ambient storage stability, and the device retained 90% of its initial efficiency after 1,000 h of heating at 80 °C (thermal) or 50% relative humidity atmospheric testing without encapsulation. Furthermore, the interaction between the facile Lewis base and various cations suppressed the related grain boundary defects, thus improving the efficiency from 19.58% of the control device to 22.43% of the target device.