Thermally Evaporated CsPbCl₃ Perovskite on Si/SiO₂ with Wide Spectrum Photoresponse from Ultraviolet (UV) to Near-Infrared (NIR)

Abstract

CsPbCl 3 metal halide perovskite photodetectors (PDs) are prepared via thermal evaporation and 75 °C in situ annealing on Si/SiO 2 substrates, and their photoresponse as well as the morphology, structure, and photophysical properties are investigated. Wide spectrum photoresponse ranging from 350 to 980 nm has been achieved with optimal responsivity (R) of 2364, 3766, and 268 A/W at wavelengths (λ) of 420, 680, and 980 nm, respectively. Such photoresponse behavior can be attributed to the parallel photoresponse from both CsPbCl 3 and Si based on the UPS (ultraviolet photoelectron spectrometry) and XPS (X-ray photoelectron spectroscopy) results. Yb 3+ doped CsPbCl 3 PDs with the photosensing layer structure of CsPbCl 3 (50 nm)/YbCl 3 (30 nm)/CsPbCl 3 (50 nm) have been prepared, and it was found that Yb 3+ dopant is capable of realizing obviously shorter exciton lifetime at 420 nm, lower trap density, as well as remarkably higher carrier mobility due to the combined effects of energy transfer from CsPbCl 3 to Yb 3+ and defect passivation from Yb 3+ , leading to remarkable improvement of the photoresponse performance with optimal R (2709, 6340 and 3573A/W), noise equivalent power (NEP) (5.64 × 10 −7 , 2.51 × 10 −7 , and 4.38 × 10 −7 W), and specific detectivity (D*) (1.84 × 10 11 , 3.24 × 10 11 , and 1.5 × 10 11 cm Hz 1/2 W −1 ) compared to those of pristine CsPbCl 3 at λ of 420, 720, and 980 nm, respectively. Especially at the NIR λ of 980 nm, 10-fold higher R is achieved after Yb 3+ incorporation. The upconversion processing of Yb 3+ can also be responsible for the enhanced wide spectrum photoresponse of Yb 3+ doped CsPbCl 3 . Our study provides a practical way to realize wide spectrum perovskite PDs by simply connecting the perovskite to Si substrates by the Au electrodes.

Effect of sandwiched YbCl3 layer thickness on exciton dynamics of Yb3+ doped CsPbCl3 perovskite photodetectors

“…Such substantial extension of the exciton lifetime can be ascribed to the quantum cutting processing of Yb 3+ ions based on the energy transfer from perovskite host to Yb 3+ dopant. The details about the energy transferring efficiency is described in our previous study [24] and the results are presented in table 1, which keeps monotonically increasing from 45.12% at 10 nm YbCl 3 to 56.66% at 40 nm YbCl 3 . The thicker YbCl 3 will promote the energy transfer from peroviskite host to Yb 3+ dopant.…”

“…For the investigation of the origin of that absorbance peak, the UV-visible absorbance spectrum of Si/SiO 2 substrate is also presented in figure 2(b) which reveals the dominant absorbance around 500 nm. We speculate that the strong absorbance around 750 nm originates from the red-shifting of the 520 nm absorbance peak of the Si/SiO 2 substrate due to the variation of reflection and refraction of the incident light after the deposition of the CsPbCl 3 on the Si/SiO 2 , and the details of the related study has been performed in our previous study [24]. Moreover, such dramatical influence of Si/SiO 2 substrates is also demonstrated in the case of Yb 3+ doping CsPbCl 3 as shown in figure 2(b).…”

“…Furthermore, the trap density of the pristine and Yb 3+ doped CsPbCl 3 is derived by capacitance (C)-voltage (V ) measurement of the perovskite device as also described in our perivous study [24].…”

“…The photo-sensing materials in our study include Yb 3+ doped CsPbCl 3 and Si substrate, so the totoal photoresponse originates from the combination of the photon absorbance of CsPbCl 3 host, Yb 3+ dopant and Si substrate as described in our previous study [24], in which the Yb 3+ photoresponse can be ascribed to the upconversion. In such process, the 4 f electrons of Yb 3+ ions are excited to the higher energy level ( 2 F 7/2 ) from 2 F 5/2 first after receiving the illumination of the NIR light, then jump to the defect level at the bottom of the conduction band followed by the final thermal excitation to the conduction band of CsPbCl 3 , leading to the generation of photocurrent [25].…”

Integration of One-Dimensional (1D) Lead-Free Perovskite Microbelts onto Silicon for Ultraviolet–Visible–Near-Infrared (UV-vis-NIR) Heterojunction Photodetectors

“…Additionally, Si exhibits great optical conductivity in the visible (vis) to near-infrared (NIR) range. Moreover, the narrow bandgap of Si makes it highly compatible with perovskite materials, − and this combination contributes to the wider spectral range and the formation of heterojunction to improve optoelectronic performance. , Therefore, it is necessary to integrate perovskites onto Si substrate to achieve broad-spectrum and high-speed detection. ,, …”