Stable Photodetectors Based on Formamidinium Lead Iodide Quantum Well Perovskite Nanoparticles Fabricated with Excess Organic Cations

Abstract

Metal halide perovskite nanoparticles have recently attracted immense interest for photodetectors due to their outstanding optical and electronic properties such as high carrier diffusion length, tunable band gap (light absorption range), and high photoluminescence (PL) efficiency. Although significant progress has been achieved in the development of perovskites, their stability is yet to be addressed. To improve the stability and quantum efficiency of FAPbI3 perovskite nanocrystals, we present a room temperature protocol to fabricate fully passivated and stable FAPbI3 nanocrystals via 2D growth in the presence of amine ligands and an excess amount of the organic cations. The crystallization mechanism of 2D colloidal quantum wells (QWs) with long-time stability is ascribed to the excess amount of large organic cations which isolate the inorganic lattice octahedral layers. It is demonstrated that the QW films (130 nm) hold 90% of their PL intensity after 30 days, which is ∼8 times more stable than FAPbI3 quantum dot (QD) films. We also show the enhanced photoresponsivity of QW photodetectors (up to 100%) as compared with QD devices. The long-term ambient performance of perovskite QW photodetectors on account of their hydrophobicity is demonstrated. The findings can shed light on a way to develop ambient stable QW nanoparticle perovskite optoelectronic devices.

Stability and spectroscopic analysis of CsPbBr3quantum dots modified with 2-n-octyl-1-dodecanol

“…According to previous studies, the long alkyl chains possessed by 2- n -octyl-1-dodecanol have certain hydrophobicity, which may be the reason for the improved stability of CsPbBr 3 QDs. 41,42 In order to further prove this inference, a water contact angle test was conducted for films with or without 2- n -octyl-1-dodecanol, and the results are shown in Fig. 7.…”

X-Graphene Quantum Dot/PbX (X = S, Se) Hybrid Nanostructures for Self-Powered Two-Color UV-NIR Photodetectors

“…On the other hand, for Se-GQD/PbSe-based devices, the photo-to-dark current ratio of ∼120 is achieved at zero bias, as shown in Figure b, making their performance quite significant among the self-powered NIR photodetectors. The rise time and fall time of these ON/OFF cycles have been calculated by the method described by Mahdi et al and are shown in Figure S2 of the Supporting Information. Rise time and fall time for S-GQD/PbS devices are 140 and 150 ms, respectively, while that of Se-GQD/PbSe devices are 170 and 180 ms, respectively.…”

“…The spectral responsivity of the detectors closely resembles the absorption spectra, which indicates that the size-dependent quantum confinement of PbS QDs determines the spectral selectivity. Other important photodetector parameters, such as specific detectivity (D*(λ)), external quantum efficiency (EQE), and noise equivalent power (NEP), have been calculated by the following formulas taken from Singh et al 57 and provided in Figure S1c−e of the Supporting Information.…”

Controlled assembly of perovskite nanoparticles by photoswitchable functional ligands

“…PeNPs are characterized by a high photoluminescence (PL) quantum yield, narrow full width at half maximum (FWHM) of emission, and tunable band gap [1]. These properties enable PeNPs to be used in light-emitting diodes [2][3][4], lasers [5,6], sensors [7,8], and photodetectors [9,10]. The ligands in PeNPs form an organic shell that plays a crucial role and affects the physical and optical properties of the NPs [11,12].…”