Quasi-two-dimensional (quasi-2D) perovskites are attracting much attention due to their impressive luminescence properties. However, the introduction of insulating bulky cations reduces the charge transport property of mixeddimensional perovskites and leads to lowered brightness and increased turn-on voltage. The trade-off between high photoluminescence quantum yield (PLQY) and electrical conductivity should be well manipulated to obtain high-performance perovskite light-emitting diodes (PeLEDs). Herein, quasi-2D perovskite BA 2 (CsPbBr 3 ) n-1 PbBr 4 -PEO with high PLQY and excellent carrier injection efficiency is demonstrated by incorporating bulky n-butylammonium bromide (BABr), CsPbBr 3 , and polyethylene oxide (PEO). BA can intercalate into the three-dimensional perovskite framework to form a layered (quasi-2D) perovskite structure. The ion conductive polymer PEO is used to protect quasi-2D perovskite crystals. Additional BABr is removed by using anhydrous isopropyl alcohol as a washing agent due to its selective dissolubility. By carefully modulating the optical and electrical properties of quasi-2D perovskite films, the maximum luminance of PeLEDs is dramatically enhanced from 191 to 33533 cd m −2 , which is the brightest green quasi-2D PeLED reported thus far, leading to an increase in external quantum efficiency from 1.81% to 8.42%. This work provides a promising route to control the optical and electrical properties of quasi-2D perovskite films for high-performance optoelectronic devices.

Layer‐by‐layer (LBL) deposition strategy enabling favorable vertical phase distributions has been regarded as promising candidates for constructing high‐efficient organic photovoltaic (OPV) cells. However, solid additives with the merits of good stability and reproducibility have been rarely used to fine‐tune the morphology of the LBL films for improved efficiency and stability. Herein, hierarchical morphology control in LBL OPV is achieved via a dual functional solid additive. Series of LBL devices are fabricated by introducing the solid additive individually or simultaneously to the donor or acceptor layer to clarify the functions of additives. Additive in the donor layer can facilitate the formation of preferable vertical component distribution, and that in the acceptor layer will enhance the molecular crystallinity for better charge transport properties. The optimized morphology ultimately contributed to high PCEs of 16.4% and 17.4% in the binary and quaternary LBL devices. This reported method provides an alternative way to controllably manipulate the morphology of LBL OPV cells.

This review summarizes the fundamentals, solution processing methods, optimization strategies and various applications of MoO3 in OPVs.

Efficient polymer solar cells (PSCs) with enhanced open-circuit voltage (Voc) are fabricated by introducing solution-processed and UV-ozone (UVO)-treated nickel acetate (O-NiAc) as an anode buffer layer. According to X-ray photoelectron spectroscopy data, NiAc partially decomposed to NiOOH during the UVO treatment. NiOOH is a dipole species, which leads to an increase in the work function (as confirmed by ultraviolet photoemission spectroscopy), thus benefitting the formation of ohmic contact between the anode and photoactive layer and leading to increased Voc. In addition, the UVO treatment improves the wettability between the substrate and solvent of the active layer, which facilitates the formation of an upper photoactive layer with better morphology. Further, the O-NiAc layer can decrease the series resistance (Rs) and increase the parallel resistance (Rp) of the devices, inducing enhanced Voc in comparison with the as-prepared NiAc-buffered control devices without UVO treatment. For PSCs based on the P3HT:PCBM system, Voc increases from 0.50 to 0.60 V after the NiAc buffer layer undergoes UVO treatment. Similarly, in the P3HT:ICBA system, the Voc value of the device with a UVO-treated NiAc buffer layer increases from 0.78 to 0.88 V, showing an enhanced power conversion efficiency of 6.64%.

Efficient perovskite/organic integrated solar cells were fabricated via vertical component engineering to enhance charge transport in an organic photoactive layer.