Atomic‐Layer Deposition‐Assisted Double‐Side Interfacial Engineering for High‐Performance Flexible and Stable CsPbBr₃ Perovskite Photodetectors toward Visible Light Communication Applications

Abstract

Self‐powered photodetectors (PDs) based on inorganic metal halide perovskites are regarded as promising alternatives for the next generation of photodetectors. However, uncontrollable film growth and sluggish charge extraction at interfaces directly limit the sensitivity and response speed of perovskite‐based photodetectors. Herein, by assistance of an atomic layer deposition (ALD) technique, CsPbBr3 perovskite thin films with preferred orientation and enlarged grain size are obtained on predeposited interfacial modification layers. Thanks to improved film quality and double side interfacial engineering, the optimized CsPbBr3 (Al2O3/CsPbBr3/TiO2, ACT) perovskite PDs exhibit outstanding performance with ultralow dark current of 10−11 A, high detectivity of 1.88 × 1013 Jones and broad linear dynamic range (LDR) of 172.7 dB. Significantly, excellent long‐term environmental stability (ambient conditions >100 d) and flexibility stability (>3000 cycles) are also achieved. The remarkable performance is credited to the synergistic effects of high carrier conductivity and collection efficiency, which is assisted by ALD modification layers. Finally, the ACT PDs are successfully integrated into a visible light communication system as a light receiver on transmitting texts, showing a bit rate as high as 100 kbps. These results open the window of high performance all‐inorganic halide perovskite photodetectors and extends to rational applications for optical communication.

Precise Phase Control of Large‐Scale Inorganic Perovskites via Vapor‐Phase Anion‐Exchange Strategy

“…For the growth of ALD-Al 2 O 3 layer, the cycling number is set to be 16 under 85 °C for 5 min, corresponding to an optimal thickness of 1.5 nm. [23] After that, the CsPbBr 3 thin films were spin-coated on the ALD-Al 2 O 3 modified FTO substrate at room temperature. First, 0.4 mol CsBr and 0.4 mol PbBr 2 were mixed and dissolved in 1 mL of dimethyl sulfoxide (DMSO) solution, which was stirred on a hot plate (70 °C).…”

“…Meanwhile, vapor phase precise control method such as atomic layer deposition (ALD) has been proved to be an ideal interface engineering technique to passivate defect states, enhance stability, as well as improve charge extraction. [23] Significantly, the proposed vapor-phase anion-exchange reaction in a chamber is proved to be a general strategy for many inorganic perovskites, where the anion-exchange rate and reaction extent can be delicately controlled. The absorption spectral resolution can be precise controlled as low as 0.8 nm by gas injection cycles and reaction temperature.…”

Room Temperature Synthesis of Phosphine‐Capped Lead Bromide Perovskite Nanocrystals without Coordinating Solvents

“…[1] They were first reported in 1893; [2] however, it took more than 100 years to reveal their true potential. [3] While perovskites were initially used for dye-sensitized solar cells, [4] the field of applications where such materials can be implemented has expanded into high-efficiency solid-state solar cells, [5] light-emitting diodes (LEDs), [6] photodetectors [7] and many other related technologies. [8] While conventional thin-film LHPs possess many attractive qualities, without passivation they have limited photoluminescence quantum yields (PLQY), [9,10] a characteristic that is vital for advancing LEDs and related devices.…”

Nano Ball‐Milling Using Titania Nanoparticles to Anchor Cesium Lead Bromine Nanocrystals and Energy Transfer Characteristics in TiO2@CsPbBr3 Architecture

“…Besides, a high temperature up to 200 °C can be produced from instantaneous heat energy of mechanical ball-grinding or ball-milling, which is enough to be exploited to form the heterojunctions. Besides, according to the previous report on CsPbBr 3 @TiO 2 thin films, [30,31] there is low interface energy between the interface of CsPbBr 3 and TiO 2 . High Gibbs free energy deriving from the mechanical and heat energy drive CsPbBr 3 and TiO 2 to form CsPbBr 3 @TiO 2 heterojunction to reduce the energy of the system.…”