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• Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising candidates for next-generation electronic and optoelectronic devices [1-5]. As a typical member in TMDCs family, molybdenum disulfide (MoS₂) gains much attention due to its excellent properties, such as layer-dependent band structure, high carrier mobility and current on/off ratio [5-8]. Moreover, as the thickness decreasing to monolayer, its energy band structure evolves to direct band gap with the value of 1.8 eV. Therefore, it is widely used as photoresponse in visible. Combing the realization of the wafer-scale growth strategy, monolayer MoS₂ has been considered as the most promising candidate to potential application in industry [5,6,9-13].

  However, the intrinsic and constant electronic structure limits the application of MoS₂. For example, its detection wavelength is usually in the visible range without reasonable photoresponse in near-infrared or further long wavelength. Moreover, the monolayer structure makes the light adsorption lower, thus, the photoelectrical conversation much lower. Therefore, the photoresponse is much lower in the range of mA/W. Although the gating tuning and ferroelectric tuning could suppress its dark current, as a result improve the photoresponse [6], the fabrication become much complex. Recently, surface decoration is utilized to further enhance the electric and photoelectric properties of the MoS₂-based devices where the introduction of additive tunes the electronic structure of MoS₂. For example, Cho et al. [14] enhanced the photocurrent of monolayer MoS₂ by coating PbS nano materials. Wang et al. [15] improved the electron concentration and source-drain current of back-gated monolayer MoS₂ transistor by surface charge transfer doping with black phosphorus (BP) nanoparticles. Different with PbS and BP, CsPbBr₃ is a typical light harvesting material in perovskite solar cells with excellent moisture and thermal stabilities [16-18]. It was applied in photodetectors with the powerful weak-light detection and ultralow dark current (< 1 pA) [16,19]. However, this application was limited by the slow light response due to the long charge transport distance between the two electrodes and the requirement of extra power amplifier [16,20,21].

  Herein, the combination of CsPbBr₃ and MoS₂ photoelectric materials was taken into consideration to achieve a photodetector with high light sensitivity, high photoelectric current and ultrahigh on/off ratio. In this purpose, the MoS₂ phototransistor was decorated by CsPbBr₃ nanoparticles in two configurations, nano-film (NF) coating and nanoparticle (NP) doping. The results of the photoelectric performance investigation showed that CsPbBr₃ NP-doping decoration can improve the current, carrier mobility and on/off ratio of the monolayer MoS₂ device, which provide a potential strategy to tune the property of MoS₂.

  Firstly, Cs₂CO₃ (0.065 g), octadecylene (ODE, 3 mL), and oleic acid (OA, 0.25 mL) was added to the three-neck flask. Then, the mixture was stirred and heated at 120 ℃ for 1 h under the nitrogen atmosphere. Finally, the Cs (oleate) solution was obtained. Simultaneously, PbBr₂ (0.144 g), ODE (10 mL), oleylamine (1 mL) and OA (1 mL) were added to another three-neck flask. And the mixture was heated at 105 ℃ for 1 h under the nitrogen atmosphere. Then the obtained Pb solution was heated to 170 ℃. Next, the Cs (oleate) solution (0.9 mL) was heated to 150 ℃ and rapidly injected to the 170 ℃ Pb solution under vigorous stirring for 5 s. Subsequently, the reaction was quenched by the ice-water bath treatment. At last, the obtained product was mixed with toluene and centrifuged for 5 min to collect the sediment.

  MoS₂ films were grown on sapphire substrate by CVD method in a two-zone tube furnace, using pre-oxidized molybdenum foil as Mo source and sulfur powder as S source. The volatilization temperature of sulfur was at 170 ℃, while the Mo source was heated at 850 ℃ under Ar flow rate of 150 sccm for growth of MoS₂.

  The as-grown MoS₂ was then transferred to the fresh SiO₂/Si substrate under assistance of PMMA layer to fabricate a back-gate field effect transistor (FET). The source and drain electrodes were pre-prepared on the SiO₂/Si substrate. Then the device was annealed at 250 ℃ for 2 h in mixed H₂-Ar gas before spin-coating with CsPbBr₃/hexane solution (1 and 0.001 mg/mL concentrations) for surface decoration. The optoelectronic property of the device was measured by a homemade vacuum probe station containing Keithley 2614B (Tektronix, US) as the source and meter. The UV–vis-NIR spectrophotometry was performed by UV-3600 (Shimadzu, Japan). The TEM images were obtained using Tecnai G2 F20S (FEI, US).

  TEM image in Fig. 1a elucidates the morphology and microstructure of the CsPbBr₃ nanoparticles (NPs), where the inset shows the size distribution based on Gaussian fits and the average size to be 45.12 ± 20.25 nm. UV–vis-NIR spectrophotometry was used to investigate the optical properties of the as-synthesized NPs and the absorption spectrum of the solution-processed CsPbBr₃ is displayed in Fig. 1b. The absorption edge is located at about 550 nm, which is consistent with the literature [16,22]. The corresponding bandgap of the NPs is derived to be 2.32 eV from a plot of (Ahv)² versus (hv) (inset of Fig. 1b) using Kubelka-Munk equations [16,23]. As shown in Fig. 1c, the XRD peaks at 2θ = 15.2°, 21.7°, 23.5°, 28.6°, 30.9°, 34.3°, 37.9° and 43.9° indicated the monoclinic phase of CsPbBr₃ (PDF #18–0364; the crystal structure is shown in the inset of Fig. 1c), which consists with the structure of the perovskite CsPbBr₃ NPs reported in literature [22,24,25]. Whilst, the phase of tetragonal CsPb₂Br₅ (PDF #25–0211; 2θ = 11.7°, 29.5°, 33.5°, 35.5°, 37.9° and 48.0°) was also observed in the XRD pattern, which might be the residuals from the CsPbBr₃ sample preparation. Some work [22,24,26] has reported that the CsPb₂Br₅ may remain in the CsPbBr₃ samples, because these two structures can reversibly transition under different temperatures. The inset of Fig. 1d displays the back-gate FET used in this study, which was fabricated by transferring as-grown MoS₂ film to the fresh SiO₂/Si substrate under assistance of PMMA layer. Then two types of surface decoration with CsPbBr₃ perovskite were proceeded for them to turning their photoelectrical properties. One transistor was spin-coated with 1 mg/mL CsPbBr₃/hexane solution for a nano-film coating decoration (NF-coating). Another one was spin-coated with 0.001 mg/mL CsPbBr₃/hexane solution for a nano-particles doping decoration (NP-doping). An obvious peak shift was found from the photoluminescence (PL) spectra of monolayer MoS₂ in Fig. 1d, which indicated an electronic band structure change for the decorating MoS₂ film. As seen, the pure MoS₂ exhibits a stronger PL intensity as compared to the NP-doped MoS₂, owing to its low lattice scattering [6]. Moreover, an intensity drop was observed after NF-coating, due to the unperfect CsPbBr₃/MoS₂ interface, which impeded the recombination of excitons, resulting in less direct band gap emission [27,28]. In addition, the sharp peak around 693 nm is for the sapphire substrate [29]. Raman spectra in Fig. 1e clearly show two typical optical vibration modes located at about 386 and 406 cm⁻¹ corresponding to the in-plane E_2g¹ mode and out-of-plane A_1g mode, respectively [6]. Fig. 1f shows the high-resolution Mo 3d spectra of the as-grown and decorated MoS₂. C 1s peak at 284.8 eV was used for the baseline calibration [30]. The peaks of the as-grown MoS₂ at 232.5, 229.3 and 226.3 eV can be assigned to the signal of Mo⁴⁺ 3d_5/2, Mo⁴⁺ 3d_3/2 and S 2s, respectively [6,31,32]. It also can be seen that a distinct shift towards lower binding energy occurred after CsPbBr₃ decorating, which indicated the electron migration from CsPbBr₃ to MoS₂ at their interface. This mechanism is also consistent with their Fermi level [25,33].

  Figure 1

  

  Figure 1.  Characterization of the CsPbBr₃ NPs and MoS₂-FET devices. (a) TEM image of the CsPbBr₃ NP; the inset shows the corresponding size distributions with Gaussian fits. (b) Absorption spectrum of the CsPbBr₃ NPs; the inset shows the Tauc plot for the corresponding absorption spectrum. (c) XRD patterns of the nanoparticle samples and the PDF cards of #18–0364 and #25–0211; the inset shows the crystal structure of the monoclinic CsPbBr₃. (d) PL spectra of MoS₂ and CsPbBr₃/MoS₂; the inset shows the representative optical microscope image of the MoS₂-FET. (e) Raman spectra of the MoS₂ and CsPbBr₃/MoS₂. (f) High-resolution XPS Mo 3d spectra of the MoS₂ and CsPbBr₃/MoS₂.

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  To well reveal the tuning of CsPbBr₃ NPs, the electrical and photoelectrical property of MoS₂ device is firstly investigated, and then in-situ decorated with CsPbBr₃ NPs. Therefore, the effect of the electrode contact property can be neglect. Fig. 2 shows the surface decoration effects of NF-coating and NP-doping for the MoS₂-FET. It was found that the threshold voltage (V_T) had a slight right shift by 3–6 V after CsPbBr₃ decoration, as a result of the p-type CsPbBr₃ doping to the n-type MoS₂ semiconductor [6,34,35]. This shift was not sensitive to the different decorating types. However, they showed different effects on the electrical property of MoS₂-FET. The I_ds of the transistor decreased by one order of magnitude at the gate voltage (V_g) of 40 V after NF-coating (Fig. 2a), which was mainly due to the electron-hole recombination at the interface between the CsPbBr₃ and MoS₂ [35,36]. The on/off ratio decreased from 10⁶ to 8 × 10³ after NF-coating. The carrier mobility (μ) decreased from 0.040 cm² V⁻¹ s⁻¹ to 0.001 cm² V⁻¹ s⁻¹ at the ΔV_g of 12 V. In addition, ΔV_g is the increment of gate voltage at the on-state current calculated by (V_g – V_T). The μ is calculated by [37]:

  (1)

  where V_ds is the basis bias voltage. C₀ is the capacitance of the SiO₂. L and W are the channel length and width, respectively. As shown in Fig. 2c, the NF-coating decoration formed a conductive film layer on the surface of the MoS₂ film, which works similarly as parallel circuit in the transistor. The hole of the NF recombined with the electron of the MoS₂ at the interface, which reduced the electron carriers in the MoS₂ and decreased its electron current. According to Tong et al. [23,38], the defects at the interface of CsPbBr₃ film usually act as charge recombination centers in devices, which significantly impedes electron carrier transport. Meanwhile, the rest hole carriers still dominated the conductive NF with a decreased hole current. Thus, the total current of the transistor decreased [39]. On the other hand, the NP-doping decoration showed an improvement in conductivity (Fig. 2b), attributing to its different action principle. As shown in Fig. 2d, the 0.001 mg/mL CsPbBr₃ doped on the MoS₂ surface instead of forming a conductive layer. At first, the hole in the NPs recombined with the electron of the MoS₂, which led to a decrease of I_ds. As V_g increases, the I_ds of the CsPbBr₃/MoS₂ transistor exceeded that of the original MoS₂ transistor from the intersection point as shown in Fig. 2b, which was due to that the higher positive V_g prompted the electron carriers of the NPs to join in the electron current in the MoS₂ film. This kind of surface charge transfer doping with NPs were also reported by Wood [40] and Wang [15]. Moreover, the on/off ratio increased from 8 × 10³ to 4 × 10⁴ after NP-doping, which was attributed to the higher on-state current and lower off-state current. The increase in on/off current ratio indicated an enhancement in controllability of conductive channel by V_g [37]. The μ value increased from 0.090 cm² V⁻¹ s⁻¹ at the ΔV_g of 7 V to 0.202 cm² V⁻¹ s⁻¹ at the ΔV_g of 5 V, which benefits the electrical property of the device [15].

  Figure 2

  

  Figure 2.  Electrical property of MoS₂ and CsPbBr₃/MoS₂. (a, b) Transfer curves of the MoS₂ and CsPbBr₃/MoS₂ transistors; the V_ds was fixed at 3 V. (c, d) Structure schematic of the NP-doped and NF-coated MoS₂ transistors. (e) The energy band diagram of CsPbBr₃ and monolayer MoS₂.

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  The threshold voltage (V_T) is the sign that the channel current (I_ds) enters on-state [37]. Fig. 3a shows the transfer curve of the NP-doped MoS₂ under 400 nm wavelength. It was found from Fig. 3b that the V_T of both the NF-coated and NP-doped MoS₂ had a positive shift by 6–9 V under 400 nm wavelength, which is not sensitive to the power density. This increment of ΔV_g was suggested to be expended by the doped p-type CsPbBr₃ with the extracted holes [41]. Responsivity (R) is defined as the photocurrent induced by the excitation of unit incident laser power and detectivity (D*) is defined as the capacity of the detector to detect weak light signals [42]. They can be calculated as following [37]:

  (2)

  (3)

  where I_p is the photocurrent, I_d is the dark current, P_opt is the optical power density, A is the effective device area and e is the electronic charge. Figs. 3c and d show the comparison of the R and D* results of the MoS₂ and CsPbBr₃/MoS₂ phototransistors at various power density under wavelength of 400 nm. It was observed that the R and D* of the phototransistor dropped by about seven times after NF-coating, which was suggested to due to that the photoelectric response of MoS₂ film was replaced by the response of the covered NF [38]. The larger bandgap of CsPbBr₃ than that of MoS₂ makes it harder for electrons to be excited from the valence band to the conduction band [6,22]. As the power density increased, more excited holes contributed to the photocurrent of CsPbBr₃, resulting in a higher photo responsivity (see the curve of NF-coated MoS₂ in Fig. 3c) [4]. Meanwhile, the R and D* of the phototransistor show a decrease after NP-doping, which was attributed to the reduction in photocurrent caused by the recombination between the hole of CsPbBr₃ NPs and the electron of MoS₂ film. Contrary to the NF-coated MoS₂, the R value decreased as the power density increased for NP-doped MoS₂, which was due to that the higher power density promotes the hole-electron recombination between the doped NPs and the MoS₂ film [43].

  Figure 3

  

  Figure 3.  Photoelectric property of MoS₂ and CsPbBr₃/MoS₂ phototransistors. (a) Transfer curve of the NP-doped MoS₂ photodetector under 400 nm wavelength. The bias voltage is fixed at 3 V. (b) Threshold voltage, (c) responsivity and (d) specific detectivity of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under 400 nm wavelength with different power density.

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  The increased electron concentration (Δn) caused by increased positive V_g can be calculated by [37]:

  (4)

  where C₀ is the capacitance of the SiO₂ and e is the charge. The carrier mobility (μ) can be obtained from the derivation of the I_ds-V_g curve, which indicates the gradient of the transfer curve. As shown in Fig. 4a, the μ curve can be divided into three regions: rise, drop and flat, corresponding to a rapid growth, slow growth and saturation of I_ds. Therefore, the three regions present the different dominant factors affecting the variation of I_ds under a rising V_g. In Region I, the value of μ has a highest growth rate and the slope is higher than 1, which indicates that the increase of carrier mobility is the dominant factor for the increase of I_ds, that is, the increase of V_g mainly affects μ [44]. In Region Ⅱ, the value of μ decreases with increasing V_g. This is due to the gradually increasing carrier concentration, which increases the scattering probability in the system. μ is inversely proportional to the scattering probability [12,45]. The current in channel can be expressed as (qnvs), where q is the electric charge, n is the carrier concentration, v is the electron velocity and s is the cross-sectional area [44]. The electron velocity can be determined as (μE), where E is the electric field. Thus, the I_ds can be expressed as [44]:

  (5)

  where n and μ are the two main contributing factors for the current. As μ is decreasing, n becomes the dominant contributor for the increasing I_ds in Region Ⅱ. In Region Ⅲ, I_ds becomes saturation with increasing V_g, where the semiconductor presents metallic property [37]. Furthermore, it was also found that its peak of variation and onset point of saturation shifted to right with higher power density (Fig. 4b), which indicates a longer lifetime of the carrier. The values of the peak and the onset point are graphed in Fig. 4c and show a linear correlation with the power density. That is, the power density can increase the carrier mobility and carrier concentration linearly, and consequently delay the time of current saturating. Fig. 4d shows the value of (Region Ⅰ/(Ⅰ + Ⅱ) × 100%) versus power density, which presents the transformation of dominant factor affecting the I_ds. The Ⅰ/(Ⅰ + Ⅱ) value of phototransistor decreased slightly with increasing power density, which indicates that the increasing power density would enhance the increment of μ under increasing V_g. The value of NP-doped MoS₂ shows a similar curve trend with a higher Ⅰ/(Ⅰ + Ⅱ) value. That is, the NP-doping can benefit the carrier mobility, which may be attributed to the lower scattering of electron [45,46]. However, the NF-coated MoS₂ threw off the trend of Ⅰ/(Ⅰ + Ⅱ) value, as a result of the compilated combination of the CsPbBr₃ and MoS₂ phototransistors.

  Figure 4

  

  Figure 4.  Analysis of photoelectric performance of MoS₂ and CsPbBr₃/MoS₂ phototransistors. (a) Segmentation of the transfer and carrier mobility curves. (b) The effect of illumination on the transfer curve and carrier mobility. The power density of the 400 nm wavelength light was 1.6 W/m². The V_ds was fixed at 3 V. (c, d) The effect of power density on the carrier concentration and mobility.

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  Fig. 5 exhibits the photoelectric properties of MoS₂ and CsPbBr₃/MoS₂ phototransistors under different wavelength of 400, 500 and 700 nm. As shown in Fig. 5b, NF-coating made the R of MoS₂ decreased from 878, 1838 and 833 A/W to 136, 178 and 367 A/W, which was attributed to the recombination between the p-type CsPbBr₃ NF and the n-type MoS₂ film. Moreover, the photoelectric response of CsPbBr₃ layer consumed part of the light energy without a significant photoelectric response and weakened the light for MoS₂ film. Also, defects of the interface would restrict the electron mobility [43]. The R of the NP-doped MoS₂ decreased from 1299, 1645 and 647 A/W to 948, 883 and 413 A/W, due to the recombination between the photogenerated hole of the doped NPs and the photoelectron of the MoS₂. Meanwhile, the D* value remains at 10¹¹ Jones after NF-coating and NP-doping. Figs. 5e and f show the rise and fall time of the photoelectric response at wavelength of 400, 500 and 700 nm. The rise (fall) time is defined as the time-resolved photocurrent increases (decreases) from 10% to 90% (90% to 10%) of the maximum photocurrent [37], which was measured under the fixed V_g at V_ds of 5 V. It was found that the NF-coating extended both the rise and fall time for MoS₂, which was caused by the shield of the CsPbBr₃ layer over the MoS₂ film. However, the NP-doping did not impact the photoresponse speed significantly.

  Figure 5

  

  Figure 5.  Photoelectric property of MoS₂ and CsPbBr₃/MoS₂ phototransistors under different wavelengths. (a) The maximum responsivity of the MoS₂ and CsPbBr₃ NP-doped MoS₂ with increasing illumination power density under different wavelengths at a gate voltage range of −60~60 V. (b, c) Responsivity and specific detectivity of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under different wavelengths. (d) Time-resolved photoresponse of the MoS₂ and CsPbBr₃ NP-doped MoS₂ under different wavelengths. (e, f) Rise and fall time of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under different wavelengths. The bias voltage is fixed at 3 V.

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  In summary, CsPbBr₃ nanoparticles were used to decorate the MoS₂ FET via NF-coating and NP-doping methods separately. It was found that the conductivity, carrier mobility and on/off current ratio of the monolayer MoS₂ were significantly improved after CsPbBr₃ NP-doping, which was suggested to due to a mixed electron recombination-injection process. Furthermore, it was found that nanofilm-coating of CsPbBr₃ would impede the photoelectric performance due to the electron-hole recombination facilitated by the defects at the interface of CsPbBr₃ and MoS₂ films. By decorating with CsPbBr₃ nanoparticles, the photoresponse of MoS₂ transistor could improve to 948 and 883 A/W at 400 nm and 500 nm illumination, and the detectivity can rise to about 10¹¹ Jones. This work may provide an easy and cost-efficient way to tune the photoresponse of MoS₂ photodetectors.

  Declaration of competing interest

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  Acknowledgmnts

  This work was financially supported by the National Natural Science Foundation of China (Nos. 52002254, 52272160), Sichuan Science and Technology Foundation (Nos. 2020YJ0262, 2021YFH0127, 2022YFH0083, 2022YFSY0045), the Chunhui plan of Ministry of Education, Fundamental Research Funds for the Central Universities, China (No. YJ201893), the Open-Foundation of Key Laboratory of Laser Device Technology, China North Industries Group Corporation Limited (No. KLLDT202104) and Supported by the fund of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP202210).

  
  
• 1. [1]

     X. Song, J. Xu, L. Liu, et al., Appl. Surf. Sci. 542 (2021) 148437. doi: 10.1016/j.apsusc.2020.148437

  2. [2]

     J. Wang, X. Xu, T. Cheng, et al., Nat. Nanotechnol. 17 (2022) 33–38. doi: 10.1038/s41565-021-01004-0

  3. [3]

     H. Huang, J. Zha, S. Li, et al., Chin. Chem. Lett. 33 (2022) 163–176. doi: 10.1016/j.cclet.2021.06.004

  4. [4]

     X. Niu, Y. Yu, J. Yao, et al., Chem. Phys. Lett. 772 (2021) 138571. doi: 10.1016/j.cplett.2021.138571

  5. [5]

     D.S. Schneider, A. Grundmann, A. Bablich, et al., ACS Photonics 7 (2020) 1388–1395. doi: 10.1021/acsphotonics.0c00361

  6. [6]

     X. Luo, Z. Peng, Z. Wang, et al., ACS Appl. Mater. Interfaces 13 (2021) 59154–59163. doi: 10.1021/acsami.1c19906

  7. [7]

     M. Liao, Z. Wei, L. Du, et al., Nat. Commun. 11 (2020) 2153. doi: 10.1038/s41467-020-16056-4

  8. [8]

     L. Wang, X. Li, C. Pei, et al., Chin. Chem. Lett. 33 (2022) 2611–2616. doi: 10.1016/j.cclet.2021.09.094

  9. [9]

     S. Luo, C.P. Cullen, G. Guo, et al., Appl. Surf. Sci. 508 (2020) 145126. doi: 10.1016/j.apsusc.2019.145126

  10. [10]

      R. Muñoz, E. López-Elvira, C. Munuera, et al., Appl. Surf. Sci. 581 (2022) 151858. doi: 10.1016/j.apsusc.2021.151858

  11. [11]

      J. Zha, M. Luo, M. Ye, et al., Adv. Funct. Mater. 32 (2022) 2111970. doi: 10.1002/adfm.202111970

  12. [12]

      L. Bu, Y. Qiu, P. Wei, et al., Phys. Rev. Appl. 6 (2016) 054022. doi: 10.1103/PhysRevApplied.6.054022

  13. [13]

      C. Zhu, I. Ahmed, A. Parsons, et al., Polym. Compos. 39 (2018) 140–151. doi: 10.1002/pc.24499

  14. [14]

      S. Cho, Y. Jo, H. Woo, et al., Appl. Sci. Converg. Technol. 26 (2017) 47–49. doi: 10.5757/ASCT.2017.26.3.47

  15. [15]

      W. Wang, X. Niu, H. Qian, et al., Nanotechnology 27 (2016) 505204. doi: 10.1088/0957-4484/27/50/505204

  16. [16]

      X. Liu, Z. Liu, J. Li, et al., J. Mater. Chem. C 8 (2020) 3337–3350. doi: 10.1039/C9TC06630F

  17. [17]

      H. Min, D.Y. Lee, J. Kim, et al., Nature 598 (2021) 444–450. doi: 10.1038/s41586-021-03964-8

  18. [18]

      R. Lin, J. Xu, M. Wei, et al., Nature 603 (2022) 73–78. doi: 10.1038/s41586-021-04372-8

  19. [19]

      W. Zhai, J. Lin, C. Li, et al., Nanoscale 10 (2018) 21451–21458. doi: 10.1039/c8nr05683h

  20. [20]

      Y. Li, Z.F. Shi, S. Li, et al., J. Mater. Chem. C 5 (2017) 8355–8360. doi: 10.1039/C7TC02137B

  21. [21]

      Y. Meng, C. Lan, F. Li, et al., ACS Nano 13 (2019) 6060–6070. doi: 10.1021/acsnano.9b02379

  22. [22]

      J. Duan, Y. Zhao, B. He, et al., Angew. Chem. Int. Ed. 57 (2018) 3787–3791. doi: 10.1002/anie.201800019

  23. [23]

      G. Tong, T. Chen, H. Li, et al., Nano Energy 65 (2019) 104015. doi: 10.1016/j.nanoen.2019.104015

  24. [24]

      K. Du, L. He, S. Song, et al., Adv. Funct. Mater. 31 (2021) 2103275. doi: 10.1002/adfm.202103275

  25. [25]

      K.C. Tang, P. YouF. Yan, Sol. RRL 2 (2018) 1800075. doi: 10.1002/solr.201800075

  26. [26]

      F. Palazon, S. Dogan, S. Marras, et al., J. Phys. Chem. C 121 (2017) 11956–11961. doi: 10.1021/acs.jpcc.7b03389

  27. [27]

      J. Choi, H. ZhangJ. H. Choi, ACS Nano 10 (2016) 1671–1680. doi: 10.1021/acsnano.5b07457

  28. [28]

      H. Ahn, Y.C. Huang, C.W. Lin, et al., ACS Appl. Mater. Interfaces 10 (2018) 29145–29152. doi: 10.1021/acsami.8b09378

  29. [29]

      T. Han, H. Liu, S. Wang, et al., Nanomaterials 9 (2019) 740. doi: 10.3390/nano9050740

  30. [30]

      C. Tan, C.D. Rudd, A.J. Parsons, et al., J. Mech. Behav. Biomed. Mater. 136 (2022) 105480. doi: 10.1016/j.jmbbm.2022.105480

  31. [31]

      A. Syari'ati, S. Kumar, A. Zahid, et al., Chem. Commun. 55 (2019) 10384–10387. doi: 10.1039/c9cc01577a

  32. [32]

      C.K. Cheng, C.H. Lin, H.C. Wu, et al., Nanoscale Res. Lett. 11 (2016) 117. doi: 10.1186/s11671-016-1277-0

  33. [33]

      X. Pan, M. Yan, C. Sun, et al., Adv. Funct. Mater. 31 (2020) 2007840.

  34. [34]

      J. Liu, F. Liu, H. Liu, et al., Nano Today 36 (2021) 101055. doi: 10.1016/j.nantod.2020.101055

  35. [35]

      T. Qin, Z. Wang, Y. Wang, et al., Nano-Micro Lett. 13 (2021) 183. doi: 10.1007/s40820-021-00710-7

  36. [36]

      B. Cao, Z. Ye, L. Yang, et al., Nanotechnology 32 (2021) 412001. doi: 10.1088/1361-6528/ac0d7c

  37. [37]

      F. Li, R. Tao, B. Cao, et al., Adv. Funct. Mater. 31 (2021) 2104367. doi: 10.1002/adfm.202104367

  38. [38]

      G. Tong, H. Li, D. Li, et al., Small 14 (2018) 1702523. doi: 10.1002/smll.201702523

  39. [39]

      D. Wang, Z. Wang, Z. Yang, et al., Mater. Today Phys. 24 (2022) 100678. doi: 10.1016/j.mtphys.2022.100678

  40. [40]

      J.D. Wood, S.A. Wells, D. Jariwala, et al., Nano Lett. 14 (2014) 6964–6970. doi: 10.1021/nl5032293

  41. [41]

      W. Chen, K. Li, Y. Wang, et al., J. Phys. Chem. Lett. 8 (2017) 591–598. doi: 10.1021/acs.jpclett.6b02843

  42. [42]

      L. Hao, Y. Du, Z. Wang, et al., Nanoscale 12 (2020) 7358–7365. doi: 10.1039/d0nr00319k

  43. [43]

      C. Chen, Y. Wu, L. Liu, et al., Adv. Sci. 6 (2019) 1802046. doi: 10.1002/advs.201802046

  44. [44]

      X.F. Zhang, L. Wei, L. Wang, et al., Appl. Phys. Lett. 102 (2013) 113501. doi: 10.1063/1.4795609

  45. [45]

      D.B. Farmer, R. Golizadeh-Mojarad, V. Perebeinos, et al., Nano Lett. 9 (2009) 388–392. doi: 10.1021/nl803214a

  46. [46]

      R. Tao, Z. Hao, C. Tan, et al., J. Electron. Sci. Technol. 20 (2022) 100167. doi: 10.1016/j.jnlest.2022.100167

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  Figure 1  Characterization of the CsPbBr₃ NPs and MoS₂-FET devices. (a) TEM image of the CsPbBr₃ NP; the inset shows the corresponding size distributions with Gaussian fits. (b) Absorption spectrum of the CsPbBr₃ NPs; the inset shows the Tauc plot for the corresponding absorption spectrum. (c) XRD patterns of the nanoparticle samples and the PDF cards of #18–0364 and #25–0211; the inset shows the crystal structure of the monoclinic CsPbBr₃. (d) PL spectra of MoS₂ and CsPbBr₃/MoS₂; the inset shows the representative optical microscope image of the MoS₂-FET. (e) Raman spectra of the MoS₂ and CsPbBr₃/MoS₂. (f) High-resolution XPS Mo 3d spectra of the MoS₂ and CsPbBr₃/MoS₂.

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  Figure 2  Electrical property of MoS₂ and CsPbBr₃/MoS₂. (a, b) Transfer curves of the MoS₂ and CsPbBr₃/MoS₂ transistors; the V_ds was fixed at 3 V. (c, d) Structure schematic of the NP-doped and NF-coated MoS₂ transistors. (e) The energy band diagram of CsPbBr₃ and monolayer MoS₂.

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  Figure 3  Photoelectric property of MoS₂ and CsPbBr₃/MoS₂ phototransistors. (a) Transfer curve of the NP-doped MoS₂ photodetector under 400 nm wavelength. The bias voltage is fixed at 3 V. (b) Threshold voltage, (c) responsivity and (d) specific detectivity of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under 400 nm wavelength with different power density.

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  Figure 4  Analysis of photoelectric performance of MoS₂ and CsPbBr₃/MoS₂ phototransistors. (a) Segmentation of the transfer and carrier mobility curves. (b) The effect of illumination on the transfer curve and carrier mobility. The power density of the 400 nm wavelength light was 1.6 W/m². The V_ds was fixed at 3 V. (c, d) The effect of power density on the carrier concentration and mobility.

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  Figure 5  Photoelectric property of MoS₂ and CsPbBr₃/MoS₂ phototransistors under different wavelengths. (a) The maximum responsivity of the MoS₂ and CsPbBr₃ NP-doped MoS₂ with increasing illumination power density under different wavelengths at a gate voltage range of −60~60 V. (b, c) Responsivity and specific detectivity of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under different wavelengths. (d) Time-resolved photoresponse of the MoS₂ and CsPbBr₃ NP-doped MoS₂ under different wavelengths. (e, f) Rise and fall time of the MoS₂ and CsPbBr₃/MoS₂ photodetectors under different wavelengths. The bias voltage is fixed at 3 V.

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