The outstanding advantages of lightweight and flexibility enable flexible perovskite solar cells (PSCs) to have great application potential in mobile energy devices. Due to the low cost, low-temperature processibility, and high electron mobility, SnO₂ nanocrystals have been widely employed as the electron transport layer in flexible PSCs. To prepare high-quality SnO₂ layers, a monodispersed nanocrystal solution is normally used. However, the SnO₂ nanocrystals can easily aggregate, especially after long periods of storage. Herein, we develop a green and cost-effective strategy for the synthesis of high-quality SnO₂ nanocrystals at low temperatures by introducing small molecules of glycerol, obtaining a stable and well-dispersed SnO₂-nanocrystal isopropanol dispersion successfully. Due to the enhanced dispersity and super wettability of this alcohol-based SnO₂-nanocrystal solution, large-area smooth and dense SnO₂ films are easily deposited on the plastic conductive substrate. Furthermore, this contributes to effective charge transfer and suppressed non-radiative recombination at the interface between the SnO₂ and perovskite layers. As a result, a greatly enhanced power conversion efficiency (PCE) of 21.8% from 19.2% is achieved for small-area flexible PSCs. A large-area 5 cm × 5 cm flexible perovskite solar mini-module with a champion PCE of 16.5% and good stability is also demonstrated via this glycerol-modified SnO₂-nanocrystal isopropanol dispersion approach.

Substitutional atomic doping of transition metal dichalcogenides (TMDs) in the chemical vapor deposition (CVD) process is a promising and effective strategy for modifying their physicochemical properties. However, the conventional CVD method only allows narrow-range modulation of the dopant concentration owing to the low reactivity of the precursors. Moreover, the growth of wafer-scale monolayer TMD films with high dopant concentrations is much more challenging. Herein, we report a facile doping approach based on liquid precursor-mediated CVD process for achieving high vanadium (V) doping in the MoS₂ lattice with excellent doping uniformity and stability. The lateral growth of the host MoS₂ lattice and the reactivity of the V precursor were simultaneously improved by introducing an alkali metal halide as a reaction promoter. The metal halide promoter enabled the wafer-scale synthesis of V-incorporated MoS₂ monolayer film with excessively high doping concentrations. The excellent wafer-scale uniformity of the highly V-doped MoS₂ film was confirmed through a series of microscopic, spectroscopic, and electrical analyses.

Silica thin films synthesized sol–gel process are proposed as flexible encapsulation materials. A sol–gel process provides a dense and stable amorphous silica structure, yielding an extremely high elastic deformation limit of 4.9% and extremely low water vapor transmission rate (WVTR) of 2.90 × 10⁻⁴ g/(m²∙day) at 60 °C and relative humidity of 85%. The WVTR is not degraded by cyclic bending deformations for the bending radius corresponding to a tensile strain of 3.3% in the silica encapsulation film, implying that the silica thin film is robust against the formation of pinhole-type defects by cyclic bending deformations. Flexible organic solar cells encapsulated with the silica films operate without degradation in power conversion efficiency for 50,000 bending cycles for a bending radius of 6 mm.