Mechanical energy derived from friction is a kind of clean energy which is ubiquitous in nature. In this research, two-dimensional graphite carbon nitride (g-C₃N₄) is successfully applied to the conversion of nitrogen (N₂) fixation through collecting the mechanical energy generated from the friction between a g-C₃N₄ catalyst and a stirring rod. At the stirring speed of 1000 r/min, the tribocatalytic ammonia radical (NH₄⁺) generation rate of g-C₃N₄ can achieve 100.56 μmol·L⁻¹·g⁻¹·h⁻¹ using methanol as a positive charge scavenger, which is 3.91 times higher than that without any scavengers. Meanwhile, ammonia is not generated without a catalyst or contact between the g-C₃N₄ catalyst and the stirring rod. The tribocatalytic effect originates from the friction between the g-C₃N₄ catalyst and the stirring rod which results in the charges transfer crossing the contact interface, then the positive and negative charges remain on the catalyst and the stirring rod respectively, which can further react with the substance dissolved in the reaction solution to achieve the conversion of N₂ to ammonia. The effects of number and stirring speed of the rods on the performance of g-C₃N₄ tribocatalytic N₂ fixation are further investigated. This excellent and efficient tribocatalysis can provide a potential avenue towards harvesting the mechanical energy in a natural environment.

Hybrid organic–inorganic perovskites have attracted intensive attention as the absorber layer in high-performance perovskite solar cells (PSCs). The interface between the electron transport layer and the perovskite layer in perovskite solar cells has a large effect on the device performance. Herein, we report a perovskite solar cell with a cell structure of ITO/ETL/(FAPbI₃)_0.97(MAPbBr₃)_0.03/spiro-OMeTAD/MoO₃/Ag, where the poly(vinylpyrrolidone) (PVP)-doped SnO₂ film works as the electron transport layer. We observe that the perovskite film grown on PVP-SnO₂ shows more uniform crystalline grains than the control sample grown on the pure SnO₂, and the electron mobility of the PVP-SnO₂ film is higher than that of the pure SnO₂ film; consequently, PVP-SnO₂ can efficiently extract electrons from the perovskite layer. As a result, the PSCs using the PVP-doped SnO₂ ETL showed an increased power conversion efficiency (PCE). The optimized device using the PVP-SnO₂ electron transport layer shows an improved PCE of 19.55%, while the PSC using the SnO₂ electron transport later shows a PCE of 17.50%. Furthermore, it is feasible to add PVP into the electron transport layer of SnO₂ to improve the performance of the planar perovskite solar cell device.

ITIC-type non-fullerene acceptors (NFAs) have attracted substantial attention in organic photovoltaics due to their advantages over fullerene derivative molecules. Briefly, the strengthened absorption coefficient, broadened spectral photoresponse, efficient exciton dissociation as well as tunable energy levels of ITIC-NFAs make them competitive components for organic optoelectronics. Here, a high-performance organic phototransistor is displayed using a simple bi-layer heterojunction of pentacene and ITIC. As a high performing semiconductor, pentacene serves as the p-type channel to transport the photo-generated carriers. Meanwhile, the representative NFA molecule, ITIC, is first applied in the organic heterojunction phototransistors (OHPTs) to improve the light detection range by extending the absorption into NIR and to enhance the light detection limit (0.3 μW cm⁻²). The maximum values of photoresponsivity (R), I_photo/I_dark ratio and external quantum efficiency (EQE) are up to 1.0 × 10⁵ A W⁻¹, 4.7 × 10⁵ and 2.0 × 10⁵%, respectively. The overall performances of our device are among the highest values in all-organic thin-film heterojunction phototransistors. These results demonstrate that ITIC-type NFAs could be highly efficient alternative acceptors for high-performance OHPTs.