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We report morphological control with phenyl-C60-butyric acid methyl ester (PCBM) molecular aggregation for perovskite–PCBM bulk heterostructure (Pe–PCBM BHS) solar cells. Solar cells prepared via the Pe–PCBM BHS method exhibited a higher power conversion efficiency (PCE) of 18% than 11% from a device with a conventional planar heterojunction structure. The Pe–PCBM BHS can enhance device efficiency by improving electron transfer, shortening the electron transport length required for collection, and reducing the charge transfer resistance at the interface between the perovskite and PCBM through an increase of the perovskite crystal size and construction of a vertical perovskite–PCBM intermixing zone. To the best of our knowledge, the high PCE achieved by our Pe–PCBM BHS is the highest value to be reported in an inverted perovskite solar cell without buffer layers, such as metal oxides or low work function metals.

Next-generation electroluminescent displays require efficient and stable red, green and blue light-emitting diodes (LEDs) with low cost, excellent color purity and flexibility, for which perovskite-based LEDs (PeLEDs) are a promising candidate. Among the three primary colors, the low efficiencies and poor stability of blue PeLEDs is the major hurdle to their commercialization. Here, we report an in situ surface engineering strategy incorporating a simple hot injection method with one pot synthesis for surface passivation of cadmium ions (Cd2+) into blue-emissive all-inorganic perovskite nanocrystals (PNCs). The optimized PNCs containing 0.2% Cd show improved photoluminescence quantum yield (PLQY; 66.8%) and ambient stability compared to the neat PNCs (25.5%) at an emission wavelength of 475 nm. PeLEDs with the PNCs show a luminance of 51 cd m−2 and EQE of 3.71%. Through a series of ab initio calculations and comprehensive XPS analysis, we show that Cd incorporation into systems with reduced dimensionality such as PNCs likely takes place via surface inclusion in the perovskite B-site, which effectively suppresses the formation of halide defects and yields enhanced device efficiencies.

Poly(3,4-ethylenedioxythiophene):poly-styrene sulfonate (PEDOT:PSS) is commonly used as a hole-transport material in optoelectronic devices such as organic and perovskite-based solar cells and light-emitting diodes. Moreover, PEDOT:PSS is suitable for fabricating flexible and roll-to-roll devices by solution processing. However, PEDOT:PSS has hygroscopic properties, and the water molecules it attracts can damage the active layer of devices, leading to reduced device stability. In this study, we develop a water-stable hole transport layer (HTL) in perovskite light-emitting diodes (PeLEDs) and organic light-emitting diodes (OLEDs) via a simple and effective method, which involves the modification of PEDOT:PSS with 2-pentacosa-10,12-diynamidoethylsulfate as a photo-crosslinking agent. Experimental results show that devices with the developed HTL show greater long-term stability than PeLEDs and OLEDs based on pristine PEDOT:PSS.