Broadband, Ultrafast, Self‐Driven Photodetector Based on Cs‐Doped FAPbI₃ Perovskite Thin Film

Abstract

In this study, a high‐performance photodetector comprised of formamidinium cesium lead iodide (FA1−xCsxPbI3) thin film is developed. The Cs‐doped FAPbI3 perovskite material is synthesized through a simple spin‐coating method, via which FA1−xCsxPbI3 with different Cs doping levels (x = 0.1, 0.15, 0.2, and 0.3) can be obtained. Further optoelectronic characterization reveals that the FA0.85Cs0.15PbI3 photodetector exhibits reproducible sensitivity to irradiation with wavelengths in the range from 240 to 750 nm, whereas it is weakly sensitive to wavelengths longer than 750 nm. The responsivity and specific detectivity are estimated to be around 5.7 A W−1 and 2.7 × 1013 cm Hz1/2 W–1, respectively. It is also worth noting that the present perovskite photodetector demonstrates an ultrafast response speed (tr/tf: 45 ns/91 ns) at zero bias voltage, which is probably related to the ultrafast lifetime and high quality of thin film according to the Hall effect study. Finally, this device shows a weak degradation in sensitivity to white light after storage at ambient condition for 45 days. The totality of the broadband sensitivity, high specific detectivity, ultrafast response speed, and self‐driven property renders the FA1−xCsxPbI3 an idea material for high‐performance photodetectors application.

A Sensitive Broadband (UV–vis–NIR) Perovskite Photodetector Using Topological Insulator as Electrodes

“…The X‐ray diffraction (XRD) pattern of the FA 0.85 Cs 0.15 PbI 3 film is displayed in Figure d. In accordance with the reported literature, the main diffraction peaks with Cs doping level of 0.15 can be indexed to black phase of FAPbI 3 . Figure e presents the XRD of the Bi 2 Se 3 film, from which a series of (0 0 n ) ( n = 3, 6, 9, 12, 15, 18) diffraction peaks belonging to space group of R3̅m/D3 5d (JCPDs No.…”

“…A schematic diagram of the TI based perovskite photodetector is presented in Figure a, in which a Cs‐doped FAPbI 3 thin film was coated directly on two parallel Bi 2 Se 3 thin films. The Bi 2 Se 3 film is comprised of quintuple layers of Se‐Bi‐Se‐Bi‐Se along the c axis, which has two different forces, weak van der Waals interactions between each quintuple layer (QL) and strong covalent bonding within each QL . The detailed fabrication process is illustrated by a flowchart in Figure S1 in the Supporting Information.…”

Recent advances on organic‐inorganic hybrid perovskite photodetectors with fast response

“…But this photodetector inevitably have slower response speed relative to other devices, which greatly limits their further development. Luo et al reported a fast‐response formamidinium cesium lead iodide (FA 1 − x Cs x PbI 3 ) photodetector and used a one‐step spin coating method to synthesize OIHP films . When x is equal to 0.15, the photodetector can obtain continuous OIHP thin film with high quality the R and D * of the FA 0.85 Cs 0.15 PbI 3 photodetector are calculated to be 5.7 A W −1 and 2.7 × 10 13 cm Hz 1/2 W −1 respectively.…”

“…C, The single normalized cycle of a photodetector used to estimate the rise and fall time. Source : Reproduced with permission from Reference Copyright 2017, John Wiley and Sons…”

A Highly Sensitive Perovskite/Organic Semiconductor Heterojunction Phototransistor and Its Device Optimization Utilizing the Selective Electron Trapping Effect

“…Considering that the concentration of Cs can directly influence the morphology/structure and consequently the optoelectronic properties of Cs‐doped FAPbI 3 perovskite, three samples with different Cs doping levels ( x = 0.1, 0.15, and 0.2) were prepared and compared in this study. Although the diffraction peaks in the X‐ray diffraction (XRD) patterns for the FA 1− x Cs x PbI 3 samples could be all assigned to the black phase of FAPbI 3 , their field emission scanning electron microscopy (FESEM) images are obviously different, as shown in Figure S1 (Supporting Information). In the case of x = 0.1 or 0.2, discontinuous perovskite films with apparent holes and defects were obtained, whereas when x was equal to 0.15, compact and continuous films with a high quality were formed (Figure S1a–c, Supporting Information).…”