A lead-free two-dimensional perovskite for a high-performance flexible photoconductor and a light-stimulated synaptic device

Abstract

Organo-lead halide perovskites have emerged as promising materials for high-performance photodetectors. However, the toxicity of lead cations in these materials limits their further applications. Here, a flexible photoconductor is developed based on lead-free two-dimensional (2D) perovskite (PEA)2SnI4via a one-step solution processing method. The flexible transparent electrodes are patterned from rGO/(PEDOT:PSS) hybrid films. The stability and reproducibility of the devices are significantly improved on adding 30 mol% SnF2 to the perovskite. The flexible photoconductors show a photoresponsivity of 16 A W-1 and a detectivity of 1.92 × 1011 Jones under 470 nm illumination, which are higher than those of most of the similar devices. Besides, the devices possess much better mechanical flexibility and durability than the flexible devices with an Au electrode. Finally, this flexible photoconductor is applied as a light-stimulated synaptic device and can mimic the short-term plasticity of biological synapses. This is the first study to report that lead-free 2D perovskite can be used in flexible photoconductors and synaptic devices.

Sn‐Based Perovskite for Highly Sensitive Photodetectors

“…Since the carrier mobility of MAPbI 3 is very close to that of FASnI 3 , the much higher responsivity cannot be correlated to the difference in the mobilities of the two materials. [13,19,28,29] Actually, high gain PDs enabled by selective trapping of photocarriers at defect states were reported before for other materials. We consider that the low photoresponse of the MAPbI 3 device is attributed to the trapping of both photogenerated electrons and holes in the perovskite layer by crystal defects and grain boundaries.…”

“…[22] Although much higher responsivity and gain can be achieved in PDs by introducing heterostructures in the devices, [22][23][24][25] the additional processing steps and materials involved in the devices may complicate the fabrication procedure and increase the cost. [27][28][29][30][31] For instance, Waleed et al fabricated a MASnI 3 nanowire-array PD by using a vapor phase chemical reaction method with porous alumina template, exhibiting a responsivity and detectivity of only 0.47 A W −1 and 8.80 × 10 10 Jones, respectively. [26] In light of this, some works have been done on lead-free perovskite-based PDs, yet satisfactory results are still lacking.…”

“…[27][28][29][30][31] For instance, Waleed et al fabricated a MASnI 3 nanowire-array PD by using a vapor phase chemical reaction method with porous alumina template, exhibiting a responsivity and detectivity of only 0.47 A W −1 and 8.80 × 10 10 Jones, respectively. [29] So, the lead-free perovskite PDs demonstrated relatively low responsivity and gain. [28] Qian et al developed a flexible PD based on (PEA) 2 SnI 4 , a 2D perovskite, with a limited responsivity of 16 A W −1 .…”

Recent Progress in Photonic Synapses for Neuromorphic Systems

“…Although MAPbI 3 ‐based photonic synapses demonstrate excellent performance, lead element in MAPbI 3 is highly toxic and it can easily pollute the environment, so that it is an enormous demand to design green devices based on lead‐free perovskites. Recently, Qian et al first fabricated a flexible photonic synaptic device based on (PEA) 2 SnI 4 , which is one kind air‐stable lead‐free 2D perovskite . The perovskite film is developed through one‐step solution approach and rGO/(PEDOT:PSS) is worked as the flexible electrode.…”

Functional Non‐Volatile Memory Devices: From Fundamentals to Photo‐Tunable Properties

“…The usage of perovskites in data storage have attracted huge amounts of interests and a number of memory devices based on inorganic or hybrid organic–inorganic perovskites (HOIP) with superior electrical performances have been investigated. Especially, because of the intense light‐harvesting property as well as significant hysteresis, perovskite materials were widely utilized to fabricate photo‐responsive memory devices, including light tunable flash memory and ReRAM . For instance, Chen et al reported a flash memory based on CH 3 NH 3 PbBr 3 (MAPbBr 3 ) displaying multilevel memory behavior by applying light illumination .…”