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Passivation defects and reducing charge recombination are of great importance in enhancing 2D perovskite solar cells' (PSCs) performance. Herein, a novel additive (TEMPIC) is introduced into 2D PSCs to improve photovoltaic properties of the device, which are mainly attributed to passivated trap-states and reduced charge recombination in device. [ABSTRACT FROM AUTHOR]

Organic small molecules have been proven to be the most efficient and predominantly employed hole transport layers (HTLs) in perovskite solar cells (PSCs), the reliance of HTLs on additives like Li‐TFSI has been unavoidable, particularly in terms of the well‐known Spiro‐OMeTAD. However, Li‐TFSI aggregation in HTL results in the decreased performance and stability of PSCs with serious hysteresis. It is an urgent need to explore a universal strategy to solve Li‐TFSI‐induced issues. Herein, a pyrene‐based organic semiconductor (PC) as an effective and universal additive for HTL application is developed. It is found that the introduction of PC can efficiently improve the hot carriers extraction/transfer and reduce the charge recombination in the device. Consequently, PSCs based on Spiro‐OMeTAD+PC as a HTL exhibit an excellent PCE of 24.80% with a negligible hysteresis, much higher than the control device (22.14%). Additionally, the efficiency of the PC incorporated into another well‐known X60 HTL‐treated device is enhanced to 24.12% from the control device (22.04%), confirming its universal application in PSCs. Moreover, PC can effectively suppress the Li+ aggregation in HTL, and the unencapsulated PSCs exhibit high stability. The findings in this work provide an effective and universal avenue to construct highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Slowing hot carrier (HC) cooling in lead halide perovskites is important to further improve the efficiency of perovskite solar cells (PSCs). Herein, we found that HC cooling can be efficiently prolonged by incorporating an organic small molecule (TDGA) into the perovskite film as an additive through transient absorption spectroscopy measurements, which is conducive to the extraction of the HC energies by the carrier transport layers and reduces charge carrier recombination, consequently improving the efficiency of the TDGA-doped device. [ABSTRACT FROM AUTHOR]

Understanding the effect of additive on the interfacial charge‐carrier transfer dynamics is very crucial to obtaining highly efficient perovskite solar cells (PSCs). Herein, we designed a simple additive, dimethyl oxalate (DO), functioning as an effective defect passivator of perovskite grain boundaries via the coordination interaction between the carbonyl (C=O) and the exposed Pb2+. The modification with DO produces pinhole‐free and compact perovskite films, enhancing the transportation capability of carriers. As a consequence, the DO‐treated PSCs exhibited a power conversion efficiency (PCE) of 22.19%, which is significantly higher than that of the control device without additive (19.58%). More importantly, detailed transient absorption characterization reveals that the use of additive can decrease the hot‐carrier cooling dynamics, improve the carrier transfer, and eliminate nonradiative recombination in PSCs. This present work provides a profound understanding the additives effect on the carrier dynamics in PSCs toward the Shockley−Queisser limit. [ABSTRACT FROM AUTHOR]

Ammonia monitoring in our daily life is significant. In this work, Ti3C2Tx/ZnO materials were prepared by hydrothermal method. The results of XRD, SEM, TEM, and XPS analyses demonstrated the successful preparation of the Ti3C2Tx/ZnO composite. Ti3C2Tx/ZnO (3:1) material exhibited the best morphology as ZnO grows evenly on it as ultrathin nanosheets. The gas sensing performance of Ti3C2Tx, ZnO, and Ti3C2Tx/ZnO (1:1, 2:1, 3:1, and 5:1) materials were studied. The Ti3C2Tx/ZnO (3:1) sensor has an excellent response to 50 ppm ammonia at a low operating temperature (∼28 °C), and the value of response is 196%, which is the highest response in this work. Furthermore, it was found that Ti3C2Tx/ZnO (3:1) detects ammonia selectively against other volatile organic compounds at a low operating temperature (∼28 °C). The actual lowest detection ability was measured at 1 ppm, and the corresponding response is 14%. The ultra-thin ZnO nanosheets on the Ti3C2Tx MXene and the p–n heterojunctions in Ti3C2Tx/ZnO (3:1) are designed to achieve better ammonia sensing performance. This paper provided a route to enhance the p-type characteristic of Ti3C2Tx MXene, which is meaningful to Ti3C2Tx MXene application at a low operating temperature in the future. [ABSTRACT FROM AUTHOR]