Controlled Anisotropic Growth Of Layered Perovskite Nanocrystals For Enhanced Optoelectronic Properties

We synthesized cubic-phase layered perovskite nanocrystals (PNCs) of different shapes, namely thin nanoplatelets, thick nanoplatelets, and nanocubes, to investigate their photoresponse characteristics in a phototransistor device. The PNCs were prepared using a one-pot hot-injection method, and their shape evolved from nanoplatelets to nanocubes (with zero-dimensional nanocrystals as a control) by controlling the reaction temperature and amount of cesium precursor. In addition, the PNCs were deposited into a film with a thickness of a few tens of nanometers by shear force using a solvent washing process combined with the spin-coating technique. The surface ligands and contaminating organic molecules were effectively removed from the deposited PNCs, and consequently, the drain current in the PNC-based phototransistors increased by 37?349% under illumination compared with the controls (purified or annealed). Of the four PNC shapes, the nanocubes showed the longest radiative lifetime and highest photosensitivity, with a photocurrent of up to 1.74 ?A cm-2 under a 3.0 V bias. This work provides in-depth insight into the dependence of the intrinsic photophysical properties of PNCs on their morphology. Moreover, the morphology of the PNCs determined how they assembled into channels to bridge the transistor electrodes, which offers new opportunities for the development of high-performance, longlifetime phototransistors and photovoltaics.