Lei Shi

Flexible perovskite solar cells (F‐PSCs) have attracted considerable interest for their superior mechanical flexibility. Nonetheless, cryptic bottom‐interface defects hinder further improvements in device performance. Here, a co‐self‐assembled monolayer (Co‐SAM) engineering strategy is implemented by integrating 4‐nitrophenyl phosphate (PNPP) into [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) butyl] phosphonic acid (Me‐4PACz) to improve the NiO _x /perovskite (PVK) interface. This technique enhanced the surface uniformity and hydrophilic nature of the NiO _x /Me‐4PACz, while promoting favorable growth of PVK crystal orientation. Furthermore, the PNPP effectively mitigates the generation of defects at the NiO _x surface and the underlying PVK, ultimately significantly improving the interfacial charge transfer efficiency. Consequently, the efficiency of F‐PSCs rose from 21.46% to 23.66%. Due to better stress distribution within the PVK and stronger adhesion at the NiO _x /PVK boundary, the F‐PSCs retained 80% of their original efficiency even after undergoing 10 000 bending cycles. Notably, PNPP exhibited an outstanding capacity to capture PbI ₂ , contributing to the potential for reducing Pb leakage of the device under operational conditions.

Thermal management is a critical task for highly integrated or high-power semiconductor devices. Low dimensional materials including graphene and single-layer hexagonal boron nitride (BN) are attractive candidates for this task because of their high thermal conductivity, semi-conductivity and other excellent physical properties. The similarities in crystal structure and chemistry between graphene and boron nitride provide the possibility of constructing graphene/BN heterostructures bearing unique functions. In this paper, we investigated the interfacial thermal transport properties of graphene/BN nanosheets via non-equilibrium molecular dynamics (NEMD) simulations. We observed a significant thermal rectification behavior of these graphene/BN nanosheets, and the rectification ratio increased with the system length increases up to 117%. This phenomenon is attributed to the mismatch of out-of-plane phonon vibration modes in two directions at the interface. In addition, we explored the underlying mechanism of the length dependence of the thermal transport properties. The results show promise for the thermal management of this two-dimensional heterostructure in an actively tunable manner.

Perovskite thin film quality, including large grain size and low defect, is one of the fundamental factors to improve the performance and stability of perovskite solar cells (PSCs). Herein, trifluoromethylphenylacetic acid (TFPA) as the accelerant of Ostwald ripening is introduced and an in situ crystal growth control (ICGC) strategy is developed to obtain high‐quality thin films. With adding a proper amount of TFPA into the FAI/MAX (X is Br and Cl) precursor in the two‐step method, the larger grain size and reduced defect density perovskite are achieved due to Ostwald ripening. The ICGC process makes the average particle size from 476 to 625 nm. The defect density is reduced by a factor of 3.18. The high‐quality thin film endows the champion PSC (SnO₂/perovskite/spiro‐OMeTAD) with a power conversion efficiency (PCE) of champion PSC higher than 22.19%. Furthermore, TFPA is insoluble in the water and thus TFPA‐modified film is resistive to moisture. The device can be stored in an argon glove box for 2000 h without efficiency change and when exposed to 65–75% relative humidity for more than 1500 h, it retains more than 85% of the initial PCE.