Controlling crystal growth and reducing number of grain boundaries are crucial to maximize the charge carrier transport in organic-inorganic perovskites field-effect transistors (FETs). Herein, the crystallization and growth kinetics of...

facile processability. [1,2] However, the application of perovskites in field-effect transistors (FETs) has received less attention and has remained challenging because of ion migration under operational conditions at room temperature due to the low formation energy of mobile ions or ionic defects in these ionic materials. [3,4] Mobile ions in perovskite FETs screen the applied gate field and reduce the gate modulation of the current yielding low fieldeffect mobility and large hysteresis. [5] In contrast, 2D Sn-based perovskites reveal favorable properties due to the insulating property of bulky organic ligands. The advantages of dielectric confinement in 2D layered structures are expected to significantly suppress ion movement in the device. [6] More importantly, the device performance can be tuned by tailoring the chemical structure of the spacer cations. [7] 2D Sn-based perovskites are promising semiconductors for high-performance FETs. [8,9] The Sn-based perovskites typically show high charge carrier mobility due to the smaller in-plane effective mass and longer carrier lifetime compared with their Pb analogs. [10] Nevertheless, there are several drawbacks to 2D Sn-based perovskite FETs. First, easy oxidation of Sn 2+ to its tetravalent state Sn 4+ , especially during solution processing, gives rise to ionic defects and leads to p-type self-doping. [11] Second, the fast Understanding and controlling the nucleation and crystallization in solutionprocessed perovskite thin films are critical to achieving high in-plane charge carrier transport in field-effect transistors (FETs). This work demonstrates a simple and effective additive engineering strategy using pentanoic acid (PA). Here, PA is introduced to both modulate the crystallization process and improve the charge carrier transport in 2D 2-thiopheneethylammonium tin iodide ((TEA) 2 SnI 4 ) perovskite FETs. It is revealed that the carboxylic group of PA is strongly coordinated to the spacer cation TEAI and [SnI 6 ] 4− framework in the perovskite precursor solution, inducing heterogeneous nucleation and lowering undesired oxidation of Sn 2+ during the film formation. These factors contribute to a reduced defect density and improved film morphology, including lower surface roughness and larger grain size, resulting in overall enhanced transistor performance. The reduced defect density and decreased ion migration lead to a higher p-channel charge carrier mobility of 0.7 cm 2 V −1 s −1 , which is more than a threefold increase compared with the control device. Temperaturedependent charge transport studies demonstrate a mobility of 2.3 cm 2 V −1 s −1 at 100 K due to the diminished ion mobility at low temperatures. This result illustrates that the additive strategy bears great potential to realize high-performance Sn-based perovskite FETs.

A novel, benign synthetic strategy towards soluble tetra(peri-naphthylene)anthracene (TPNA) decorated with triisopropylsilylethynyl substituents has been established. The compound is perfectly stable under ambient conditions in air and features intense and strongly bathochromically shifted UV/vis absorption and emission bands reaching to near-IR region beyond 900 nm. Cyclic voltammetry measurements revealed four facilitated reversible redox events comprising two oxidations and two reductions. These remarkable experimental findings were corroborated by theoretical studies to identify the TPNA platform a particularly useful candidate for the development of functional near-IR fluorophores upon appropriate functionalization.