High‐Performance Non‐Volatile Flash Photomemory via Highly Oriented Quasi‐2D Perovskite

Abstract

Solution‐processable organic–inorganic hybrid perovskite materials have been applied to a variety of optoelectronic devices due to its long exciton lifetime and small binding energy. It has emerged as promising front‐runners for next‐generation non‐volatile flash photomemory devices. However, the effect of crystal orientation of perovskite on the performance of photomemory still has not fully developed. Herein, non‐volatile flash photomemory with quasi‐2D perovskite/polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) as photoactive floating‐gate and p‐type semiconductor poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as the chare‐transporting layer is successfully demonstrated. By adding phenylethylammonium bromide (PEABr) in formamidinium lead bromide perovskite (FAPbBr3), the crystal orientation of quasi‐2D perovskite is highly improved, which results in raised charge transfer efficiency from 76% to 90% compared to the pure FAPbBr3. Furthermore, ON/OFF current ratio of 104, low photo‐programming time of 5 ms under light intensity of 0.85 mW cm−2, charge transfer rate of 0.063 ns−1, and data storage capacity of over 7 bits (128 levels) in one cell can be achieved. In addition, the correlation between photo‐responsive current and photoluminescence (PL) is first examined by in operando PL measurement, which provides a new platform to explore the charge transfer process in photomemory.

Improving the Photoresponse of Transistor Memory Using Self-Assembled Nanostructured Block Copolymers as a Photoactive Electret

“…The decay tendency of the memory device upon fast light pulses was calculated by using a biexponential fitting, and the average time constant (τ) was obtained by the following equation according to a reported method …”

“…Owing to the miniaturization of the electronic device, physical interactions in nanoscales have become increasingly important. 36−38 Recently, strategies have been exerted on the electrets of phototransistor memory primarily using (i) chelation between polymer−perovskite based on Lewis acid−base association, 39 (ii) hydrogen bonding, 40 and (iii) charge-transfer interaction 35 to produce the optoelectronic characteristics. However, little attention has been given to directly tailor photoactive and nanostructured BCP electrets into phototransistors.…”

“…In addition, the optimized CT interaction between pyrene and TCNQ endows the materials with favorable molecular association, photoelectrical properties, and charge ordering, conducing to the better retention capability and bistable switching phenomenon. Owing to the miniaturization of the electronic device, physical interactions in nanoscales have become increasingly important. − Recently, strategies have been exerted on the electrets of phototransistor memory primarily using (i) chelation between polymer–perovskite based on Lewis acid–base association, (ii) hydrogen bonding, and (iii) charge-transfer interaction to produce the optoelectronic characteristics. However, little attention has been given to directly tailor photoactive and nanostructured BCP electrets into phototransistors.…”

A brief review on device operations and working mechanisms of organic transistor photomemories

“…Owing to the strong light-harvesting capability, low exciton binding energy, and long charge carrier lifetime (>100 ns) and diffusion length (>1 μm), inorganic perovskite-based materials have been chosen as versatile and promising photoresponsive materials. 24,40,59–63 For photomemory applications, typically perovskite nanoparticles (NPs) will be mixed with polymer insulation to control the film morphology and suppress the formation of the continuous perovskite film that might favor a pass way for depleting the trapped charges. 24,64 By this method, the formation of the charge storage layer could be regarded as the floating gate type.…”

Novel Application of Phosphorescent Material for Non‐Volatile Flash Photomemory and Artificial Photonic Synapse

“…[46] Therefore, supramolecular assemblies of BCPs with functional materials have provided a prevailing platform to exploit the morphological effect on the performance of relevant optoelectronic devices, especially in the field of transistor-type memory. [17,18,46,[49][50][51][52] However, the development of phosphorescent material combined with BCPs as the floating gate in photomemory has not been studied in detail.…”