Nanosecond-Response Speed Sensor Based on Perovskite Single

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Nanosecond-Response Speed Sensor Based on Perovskite Single Crystal Photodetector Array Jie Ding, Yu Liu, Huajing Fang, Yingxin Wang, Qiang Li, Jia-Lin Sun, and Qingfeng Yan ACS Photonics, Just Accepted Manuscript • DOI: 10.1021/acsphotonics.8b00397 • Publication Date (Web): 14 May 2018 Downloaded from http://pubs.acs.org on May 14, 2018

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Nanosecond-Response Speed Sensor Based on Perovskite Single Crystal Photodetector Array Jie Ding,† Yu Liu,‡ Huajing Fang,† Yingxin Wang,§ Qiang Li,† Jia-Lin Sun,‡* Qingfeng Yan†*



Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education,

Department of Chemistry, Tsinghua University, Beijing 100084, China. E-mail: [email protected] (Q. Yan) ‡

Collaborative Innovation Center of Quantum Matter, State Key Laboratory of Low-Dimensional

Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China. E-mail: [email protected] (J.-L. Sun) §

Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education,

Department of Engineering Physics, Tsinghua University, Beijing 100084, China

ABSTRACT: A nanosecond-response speed sensor is demonstrated based on a CH3NH3PbI3 perovskite single crystal photodetector array. The responsivity of the CH3NH3PbI3 photodetector unit is as high as 1.55×102 A/W under 1.93×10-2 mW/cm2 illumination with 532 nm laser. The ultrafast response time less than 12.5 ns makes it possible for ultrahigh speed detection. Owing to the uniformity of as-prepared CH3NH3PbI3 single crystal, each array element shows a consistent performance. When a shelter moves across the photodetector array, the time delay of the photoresponses between two neighboring array elements can be recorded promptly.

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Therefore, speed of the moving shelter can be calculated easily. Besides speed sensing, the ability of capturing the trajectory of a moving object is also demonstrated. The nanosecondresponse speed sensor presented here demonstrates great potential for applying in high-speed detection.

KEYWORDS: speed sensor, perovskite, single crystal, ultrafast, stability

High-speed detection is crucial for applications like fast moving object measurement, fast imaging and ultrafast dynamic processes simulation.1,2 Nowadays, the speed detection methods can be mainly divided into two types, i.e. contact and non-contact method. For example, Wang et al. reported a ZnO nanowires-based speed sensor. On the one hand, the ZnO nanowires served as a nanogenerator to harvest energy from the motion of a vehicle. On the other hand, the nanogenerator exhibited the function of monitoring the vehicle speed by contacting the vehicle tire.3,4 However, the measurement accuracy of this contact method is limited by the moving conditions like wheels beating, slipping, and inflating. As a representative of non-contact measuring methods, photodetector (PD) as a fundamental pixel in optoelectronics has been used to detect the moving objects, but the speed of which is limited to only around meters per second owing to the limitation of semiconductor materials used.5,6 There is therefore an urgent and significant need to develop high-speed detection techniques superior to existing technologies. Among numerous semiconductor material candidates for PD, organic-inorganic hybrid perovskites have received increasing interests due to their high carrier mobility, long carrier lifetime, long diffusion length and so on.7-13 Xie et al. reported the CH3NH3PbI3 perovskite PD firstly which showed a responsivity (R) of 0.0367 A/W and a response time of 100 ms at 780 nm

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with a bias of 3 V.14 Yang et al. demonstrated a CH3NH3PbI3 perovskite PD, which exhibited detectivity to weak signals (8×1013 Jones) and fast photoresponse (180 ns).15 Horvath et al. reported PD based on CH3NH3PbI3 perovskite nanowires that reached R of 5 mA/W and response time less than 500 µs.16 Huang et al. presented CH3NH3PbI3 film PD with an ultrafast response time of ~1 ns with a responsivity of 0.47 A/W when the device area was as small as 0.04 mm2.17 Later, they also reported self-filtered narrowband perovskite PDs which had a response time of ~600 ns with a 8 mm2-area device.18 Luo et al. reported a formamidinium cesium lead iodide film PD which demonstrated a R of 5.7 A/W and an ultrafast response time of 45 ns.19 Recently, it has been recognized that perovskite single crystal PD shows a better performance than its polycrystalline film counterpart owing to the lower defects and charge traps density.20,21 Huang et al. demonstrated a CH3NH3PbI3 thin single crystal PD which had a response time of 300 ns.22 Besides the single PD element, array of PDs has also been successfully achieved based on organic-inorganic hybrid perovskite materials. Deng et al. reported a network PD array based on CH3NH3PbI3 perovskite nanowires, which realized spatial imaging assisted with two probes.23 Liu et al. reported a series of large perovskite single crystal wafer.24 It provided a way for mass production of independent optoelectronic devices with superior performance. Saidaminov et al. also reported a way to grow large-scale perovskite microcrystalline film which exhibted high-performance.25 Although both PD single element and array based on organic-inorganic hybrid perovskites have demonstrated impressive performance, e.g., high responsibility and fast photoresponse, their applications in speed sensing have not yet been reported. Herein, we firstly report a high-speed sensor based on a PD array on the (100) facet of CH3NH3PbI3 perovskite single crystal. It demonstrates a high R up to 1.55×102 A/W under

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1.93×10-2 mW/cm2 illumination and a fast response time of less than 12.5 ns. Each pixel or PD element showed a high uniformity owing to the smooth and defect-free surface of the as-grown CH3NH3PbI3 single crystal. Benefit from the fast response of each PD element, the time delay of the photoresponses between two neighboring array elements can be recorded promptly when a shelter moves across the photodetector array. Therefore, speed of the moving shelter can be calculated easily. Besides speed measurement, the ability of this PD array to track the trajectory of a moving object is also demonstrated.

Figure 1. a) Schematic illustration of a PD array on the (100) facet of CH3NH3PbI3 single crystal. The yellow areas reprent gold electrodes. A beam focusing on one PD is highlighted with green color. b) Photoresponse of the pixel 1 under 25 cycles of 532 nm illumination. c) R for pixel 1 under 532 nm laser illumination with different intensities. d) EQE for pixel 1 from 375 nm to 808 nm illumination.

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To make the device, CH3NH3PbI3 single crystals were first grown by solution temperaturelowering method.26 The powder XRD pattern proves that all the diffraction peaks can be assigned to a perovskite structure and the UV-Vis absorption spectrum verifys the absorption edge of CH3NH3PbI3 is 835 nm (Figure S1, Supporting Information). By simply depositing Au electrodes were deposited on the naturally-exposed and smooth (100) facet of the single crystal with the same channel of 30 µm in length and 1 mm in width, pixel in a row separated by 0.45 mm. The PD array composed of 4 pixels is schematically shown in Figure 1a. We first measured the photoresponse of each pixel of the PD array. For each pixel, it worked as an independent PD. The current-time curve of pixel 1 was detected as shown in Figure 1b under 532 nm illumination. More than 25 switching cycles were performed at a bias of 1 V under 1.7 mW/cm2 and pixel 1 exhibited a stable on/off ratio of 6. The working mechanism of the photodetector is demonstrated in detail in Figure S2, Supporting Information. The responsivity R is a key parameter to evaluate the performance of the PD, which can be defined as follow: =

   ×

, where IL is the light current when light is on, ID is the dark current when light is off,

P0 is the irradiance power density and S0 is the effective illuminated area. As shown in Figure 1c, R was calculated to be 2.07 A/W when the irradiance power density was 2.67×102 mW/cm2. It increased to 1.55×102 A/W when the irradiance power density decreased to 1.93×10-2 mW/cm2. The external quantum efficiency (EQE) can be defined as: =

 

, where R is the

responsivity, h is the Planck’s constant, c is the speed of light, e is the electron charge, λ is the wavelength of incident light. The EQE was 3.8×103 %, 4.7×103 %, 3.6×103 %, 4.3×103 %, 2.0×103 %, 1.1×103 % under 375, 405, 532, 633, 785, 808 nm light illumination separately

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(Figure 1d). The high EQEs as well as the broadband response indicate the excellent performance of the CH3NH3PbI3 single crystal PD.

Figure 2. Photoresponse of the pixel 1 under relatively low frequency: a) 500 Hz, b) 3000 Hz, c) 4000 Hz, d) 5000 Hz.

The response time is another key parameter of a PD’s performance and determines the ability of speed sensing of the PD array. To evaluate the potential of the PD array under different work conditions, e.g., low frequency and high frequency, we tested the photoresponse of pixel 1 as shown in Figure 2a-d and Figure 3a-c. First, under a low frequency ranging from 500 Hz to 5000 Hz provided by a mechanical chopper, the response time can be determined as 2.3×10-4 s, 3.1×10-5 s, 1×10-5 s, 8.3×10-6 s separately. Here the response time is defined as the time taken from the initial photocurrent to 80 % increase. The nominal slower response time under lower frequency can be attributed to the limitation of optical chopper’s rotating speed. All the response

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period was in perfect accordance with the chopping frequency. Then, we used a pulse laser to replace the mechanical chopper, which facilitated the high frequency measurements as shown in Figure 3a-c. Under 532 nm ps pulse laser, the PD showed a response time of 3.44×10-6 s and 1.4×10-7 s under 30 KHz and 1 MHz respectively. The pixel 1 could even faithfully response to the light with a 100 fs (80 MHz) pulse laser (Figure 3c), which indicates a response time less than 12.5 ns. This ultrafast response time makes it possible for high speed detection. The regular response jitter observed in Figure 3c might be caused by photo-induced carriers’ multiple effect.27,28 The pixel’s excellent response from low frequency to high frequency provided a broad speed measurement range for the PD array.

Figure 3. Photoresponse of the pixel 1 under relatively high frequency: a) 30 KHz, b) 1 MHz, c) 80 MHz.

Besides the excellent performance of each PD pixel, the uniformity of all the PD pixels is very important for a PD array. An equivalent circuit when the photodetector array works as a speed sensor is schematically shown in Figure S3, Supporting Information. The actual measurement setup and photo of the device are shown in Figure S4-5, Supporting Information. Owing to the resistors were connected to PDs in series, we defined the specific responsivity   to describe the photoresponse of each pixel (  =

  

 ×

, where  is the light current when light is on,  is the

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dark current when light is off, P0 is the irradiance power density and S0 is the effective illuminated area.). The   of the PD array was tested at 532 nm under irradiance power density ranging from 0.256 to 267.5 mW/cm2. All measurements were performed in air at room temperature. As illustrated in Figure 4a-e, when the incident light focused on pixel 1, the other 3 pixels showed almost negligible response above 0.256 mW/cm2 incident light. The extracted light current and dark current were 16.67 µA and 0.46 µA respectively upon 267.5 mW/cm2 irradiance. When the power density of the incident light increased, it can be clearly seen that the photocurrent increased accordingly. Photoresponse of other three pixels were demonstrated in Figure S6, S7, S8, Supporting Information, respectively. Moving the focused light from pixel 1 to pixel 4, each pixel worked fine and equally as shown in Figure 4f. These results prove sufficiently that each pixel could work well with uniform performance. The good and uniform performance benefits mainly from the high crystalline quality of the CH3NH3PbI3 perovskite single crystal, which also lays a solid foundation for speed detection.

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Figure 4. Photoresponse of the CH3NH3PbI3 single crystal PD array at 532 nm under different irradiance power density. a) 0.256, b) 8.823, c) 21.71, d) 80.72, e) 267.5 mW/cm2. f)   with different irradiance power density for 4 different pixels.

Next, speed measurement was demonstrated by using the PD array. When a non-tranparant object moved across pixel 1 and pixel 2 under light illumination, the time delay between the photoresponse of pixel 1 and pixel 2 could be used to measure the speed of the moving object. To demonstrate the working principle, as schematically shown in Figure 5a, an optical chopper is put between the light source and the PD array. When the optical chopper runs, the blade of the optical chopper will shelter the light illumination on one pixel periodically. An oscilloscope is used to detect the photovoltage change of each pixel. The speed of the moving blade depends on the running frequency of the optical chopper. Obviously, the photoresponse of two neighboring pixels, e.g. pixel 1 and pixel 2, will show a time delay ∆t (defined as the time difference taken from the initial photocurrent to 80% increase from pixel 1 to pixel 2) when the blade is moving from pixel 1 to pixel 2. Such a response delay was calculated to be 0.53 ms, 53.8 µs, 17.79 µs, 10.8 µs from Figure 5b-e under 100 Hz, 1000 Hz, 3000 Hz, 5000 Hz running frequency respectively. The distance from pixel 1 to pixel 2 was measured as 0.45 mm. The speed of the

moving blade of the running optical chopper could be calculated simply by equation  = ,  where V represents the speed of the moving blade shelter, S represents the distance it passes, t represents time it consumes. The speed of the blade shelter was calculated to be 0.84, 8.36, 25.30, 41.67 m/s. In fact, the optical chopper worked at a frequency of 100, 1000, 3000, 5000 Hz, meaning the real line speed of the blade shelter was 0.84, 8.37, 25.12, 41.80 m/s (Figure S9, Supporting Information). The relative error between the measured value and the real one was

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only 0.00, 0.10, 0.70, 0.30 %, which indicated the high accuracy of the PD array as a speed sensor. Considering the response time of the single PD pixel was on the nanosecond level (< 12.5 ns), it is expected the PD array could detect even faster object such as a moving bullet with a speed of hundreds meter per second.

Figure 5. a) Illustration of speed measurement based on a CH3NH3PbI3 single crystal PD array. Photoresponse of pixel 1 and pixel 2 to a moving shelter under b) 100 Hz, c) 1000 Hz, d) 3000 Hz, e) 5000 Hz.

The stability of organic-inorganic hybrid perovskites has always been an issue people concerned. To demonstrate the stability of the speed sensor, we measured the photoresponse of the PD array after stored 5 months, as shown in Figure 6a-d. Without encapsulation, the device was exposed directly to an ambient environment at room temperature and with 20–40% humidity, which was controlled with a laboratory ventilation system and in-situ monitored with a

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digital temperature and humidity meter. The response delay between pixel 1 and 2 was calculated to be 0.54 ms, 50.2 µs, 17.70 µs, 9.7 µs from Figure 6a-d when the mechanical chopper was running at 100 Hz, 1000 Hz, 3000 Hz, 5000 Hz respectively. Among all the test results, the biggest absolute error was calculated to be 3.6 µs (relative error 6.69 %) comparing with the fresh device (Figure 6e). Accordingly, the speed of the blade of the mechanical chopper can be calculated to be 0.83, 8.96, 25.40, 46.39 m/s. By comparing the tested results and calculated speed as shown in Figure 6f, the biggest measurement error was 10.98 % between the device after stored 5 months and real speed when the mechanical chopper worked at 5000 Hz.

Figure 6. Photoresponse of pixel 1 and pixel 2 to a moving shelter under a) 100 Hz, b) 1000 Hz, c) 3000 Hz, d) 5000 Hz after 5 months. e) Measureed photoresponse time delay between pixel 1 and pixel 2 before and after stored 5 months. f) A comparison of the calculated and tested blade shelter’s speed.

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Besides speed sensing, the CH3NH3PbI3 single crystal PD array could also monitor the trajectory of a moving object. To illustrate this function, a beam expander was used to expand the diameter of a 532 nm laser beam till the light covered the whole PD array (~ 0.785 cm2) as schematically shown in Figure 7a. Owing to inhomogeneity of the irradiance light after beam expanding, it turned to a specific optical field distribution, which caused a corresponding photocurrent distribution in the four pixels as shown in Figure 7b. As schematically shown in Figure 7c, when a small spherical shelter (diameter ~2 mm) moved straight from spot A to spot B, meaning it crossed the pixel 1 while stopped before the pixel 3, the photocurrent of pixel 1 would show a corresponding response while pixels 2, 3, 4 had no response as shown in Figure 7d. It can be calculated the object moved at a speed V1 of 0.0012 m/s. V1 was calculated by  =

 

, where V1 represents the speed of the moving spherical shelter, d represents the

diameter of the shelter (~2 mm), L represents the the channel length (30 µm), and t1 represents time it consumes (1.75 s). When a large shelter (1 mm × 8 mm) moved parallel from spot A to spot B fast as schematically shown in Figure 7e, it would induce an apparent photocurrent decrease in both pixel 1 and pixel 3 while the photocurrent of pixel 2 and pixel 4 remained unchanged as shown in Figure 7f. V2 of the shelter was calculated to be 0.0013 m/s by using the equation  =



!

!

, where V2 represents the speed of the moving blade shelter, W1 represents

the width of the shelter (1 mm), W2 represents the channel width (1 mm), and t2 represents time it consumes (1.5 s). Furthermore, when a shelter moved with a specific angle as schematically shown in Figure 7g, it also could be detected by the difference between the photoresponse of the four pixels as shown in Figure 7h. Use the equation set: tan % = 

12/ 0

&

'& ×∆



, ) × *) = + + -./ 0 +

, where V3 represents the speed of the moving blade shelter, θ represents the angle between

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the movement direction and the direction parallel, ∆t is the time delay of photoresponse from pixel 1 to pixel 3 (or from pixel 2 to pixel 4) (0.053 s), W3 humiepresents the width of central gap (1.03 mm), t3 represents the time which consumes moving across pixel 3 (1.5s) (Figure S10, Supporting Infomation). V3 was calculated to be 0.0013 m/s, θ was calculated to be 86°. Therefore, the trajectory of a moving object could be monitored accordingly by analyzing the photoresponse of the CH3NH3PbI3 single crystal PD array.

Figure 7. (a) Expanding light to cover the whole PD array. (b) Photoresponse of the PD array corresponding to a. (c) Small shelter moves from spot A to spot B slowly. (d) Photoresponse of the PD array corresponding to c. (e) Large shelter moves from spot A to Spot B fast. (f) Photoresponse of the PD array corresponding to e. (g) Large shelter moves from spot A to spot B with an angle. (h) Photoresponse of the PD array corresponding to g. Dashed lines stand for the moving trajectory.

In summary, we demonstrated a nanosecond-response speed sensor based on a CH3NH3PbI3 perovskite single crystal PD array. The solution-grown single crystal owed a large size and good

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uniformity, leading to excellent and uniform performance of each PD pixel. Under 532 nm light illumination, the R was as high as 1.55×102 A/W. Owing to the fast response time of less than 12.5 ns, the PD array was able of detecting a moving object of high speed with high accuracy. Take a running optical chopper working at 5000 Hz as a sample, the line speed of its blade was measured to be 41.67 m/s with a relative error of only 0.3 %. In addition, the trajectory of a moving object could be also monitored by analyzing the photoresponse of the CH3NH3PbI3 single crystal PD array. The nanosecond-response speed sensor presented here demonstrates great potential for applying in high-speed detection. METHODS Growth of CH3NH3PbI3 Perovskite Single Crystal: The growth method was detailed in our previous report.19,20 Briefly, PbCl2 (99.5%, Sinoreagent) and CH3NH2 solutions (40 wt% aqueous solution, Aladdin) in a molar ratio of 1:1 were dissolved in HI (57 wt% aqueous solution, Acros Organics) separately. The two solutions were mixed at a high temperature and stirred till the solution turned homogeneous. CH3NH3PbI3 single crystal was attained by slowly cooling down the solution to 50 °C in two weeks. Photoresponse Characteristics: 30 nm Au was deposited on the (100) facet of the CH3NH3PbI3 single crystal as electrodes, forming photodectors with a planar structure. The photoresponse of the device was measured under 1 V bias provided by a digital Sourcemeter (Keithley 2400). A laser equipped with a manual monochromator provided light source (MDLIII-785 nm-500 mW-15041405, MGL-III-532 nm-200 mW-15020332, MDL-III-375 nm-100 mW-15030369, MRL-III-633 nm-100 mW-15040733). The light was filtered by an optical chopper (Rayscience Optoelectronic innovation Co., Ltd C-995).The incident power density was calibrated by a set of optical power meter. The electrical signals were collected by a Keithley

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2400 Sourcemeter and a Source/Measure Unit (Agilent B2911A). The fast speed detection was measured by a ps laser (EdgeWave GmbH px100-2-GH), femtosecond laser (CoHerent Vitesse5W) operator and an oscilloscope (Techtronix DPO5104B).

ASSOCIATED CONTENT The Supporting Information is available free of charge on the ACS Publications website. XRD, UV-Vis-NIR absorption spectrum, working mechanism of CH3NH3PbI3 PD device, photoresponse of each pixel, calculation of the optical chopper’s speed and moving shelter’s speed. AUTHOR INFORMATION Corresponding Author *Email: [email protected] (Q. Yan) *E-mail: [email protected] (J.-L. Sun) Author Contributions All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS

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This work was supported by Science Challenge Project (No. TZ2018004). The Tsinghua University Initiative Scientific Research Program (No. 20161080165) and the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (No. KF201516) are also acknowledged for partial financial support. The authors thank Prof. Guisheng Zou, Prof. Lei Liu and Mr. Songling Xing from Department of Mechanical Engineering, The State Key Laboratory of Tribology, Tsinghua University for the help on supporting ps laser operator. REFERENCES (1) Wang, X.; Tian, W.; Liao, M.; Bando, Y.; Golberg, D. Recent advances in solutionprocessed inorganic nanofilm photodetectors. Chem. Soc. Rev. 2014, 43, 1400. (2) Koppens, F. H. L.; Mueller, T.; Avouris, P.; Ferrari, A. C.; Vitiello, M. S.; Polini, M. Photodetectors based on graphene, other two-dimensional materials and hybrid systems. Nat. Nanotechnol. 2014, 9, 780-793. (3) Lin, L.; Hu, Y.; Xu, C.; Zhang, Y.; Zhang, R.; Wen, X.; Wang, Z. Transparent flexible nanogenerator as self-powered sensor for transportation monitoring. Nano Energy 2013, 2, 75-81. (4) Hu, Y.; Xu, C.; Zhang, Y.; Lin, L.; Snyder, R. L.; Wang, Z. A Nanogenerator for Energy Harvesting from a Rotating Tire and its Application as a Self-Powered Pressure/Speed Sensor. Adv. Mater. 2011, 23, 4068. (5) Fabian, T.; Brasseur, G. A measurement algorithm for capacitive speed encoder with a modified front-end topology. Transactions on Instrumentation and Measurement, 2002, 47, 1341-1345. (6) Koeppe, R.; Neulinger, A.; Bartu, P.; Bauer, S. Video-speed detection of the absolute

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position of a light point on a large-area photodetector based on luminescent waveguides. Opt. Express, 2010, 18, 2209-2218. (7) Sutherland, B. R.; Johnston, A. K.; Ip, A. H.; Xu, J.; Adinolfi, V.; Kanjanaboos, P.; Sargent E. H. Sensitive, fast, and stable perovskite photodetectors exploiting interface engineering. ACS Photonics, 2015, 2, 1117-1123. (8) Dong, Q.; Fang, Y.; Shao, Y.; Mulligan, P.; Qiu, J.; Cao, L.; Huang, J. Electron-hole diffusion lengths > 175 µm in solution-grown CH3NH3PbI3 single crystals. Science, 2015, 347, 967-970. (9) Shi, D.; Adinolfi, V.; Comin, R.; Yuan, M. J.; Alarousu, E.; Buin, A.; Chen, Y.; Hoogland, S.; Rothenberger, A.; Katsiev, K.; Losovyj, Y.; Zhang, X.; Dowben, P. A.; Mohammed, O. F.; Sargent, E. H.; Bakr, O. M. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals. Science, 2015, 347, 519-522. (10) Saidaminov, M. I.; Abdelhady, A. L.; Murali, B.; Alarousu, E.; Burlakov, V. M.; Peng, W.; Dursun, I.; Wang, L.; He, Y.; Maculan, G.; Goriely, A.; Wu, T.; Mohammed, O. F.; Bakr, O. M. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization. Nat. Commun. 2015, 6, 7586. (11) Liu, Y.; Yang, Z.; Cui, D.; Ren, X.; Sun, J.; Liu, X.; Zhang, J.; Wei, Q.; Fan, H.; Yu, F.; Zhang, X.; Zhao, C.; Liu, S. Two-inch-sized perovskite CH3NH3PbX3 (X = Cl, Br, I) crystals: growth and characterization. Adv. Mater. 2015, 27, 5176. (12) Lian, Z.; Yan, Q.; Gao, T.; Ding, J.; Lv, Q.; Ning, C.; Li, Q.; Sun, J. -L. Perovskite CH3NH3PbI3(Cl) single crystals: rapid solution growth, unparalleled crystalline quality, and low trap density toward 108 cm-3. J. Am. Chem. Soc. 2016, 138, 9409. (13) Li J.; Yuan S.; Tang G.; Li G.; Liu D.; Li J.; Hu X.; Liu Y.; Li J.; Yang Z.; Liu S. F., Z. Liu,

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Gao F.; Yan F. High-performance, self-powered photodetectors based on perovskite and graphene. ACS Appl. Mater. Inter. 2017, 9, 42779-42787. (14) Hu, X.; Zhang, X.; Liang, L.; Bao, J.; Li, S.; Yang, W.; Xie, Y. High-performance flexible broadband photodetector based on organolead halide perovskite. Adv. Funct. Mater. 2014, 24, 7373-7380. (15)Dou, L.; Yang, Y.; You, J.; Hong, Z.; Chang, W.; Li, G.; Yang, Y. Solution-processed hybrid perovskite photodetectors with high detectivity. Nat. Commun. 2014, 5, 5404. (16) Horvath, E.; Spina, M.; Szekrenyes, Z.; Kamaras, K.; Gaal, R.; Gachet, D.; Forro, L. Nanowires of Methylammonium Lead Iodide (CH3NH3PbI3) Prepared by Low Temperature Solution-Mediated Crystallization. Nano Lett. 2014, 14, 6761-6766. (17)Shen, L.; Fang, Y.; Wang, D.; Bai, Y.; Deng, Y.; Wang, M.; Lu, Y.; Huang, J. A selfpowered, sub-nanosecond-response solution-processed hybrid perovskite photodetector for time-resolved photoluminescence-lifetime detection. Adv. Mater. 2016, 28, 10794-10800. (18) Li, L.; Deng, Y.; Bao, C.; Fang, Y.; Wei, H.; Tang, S.; Zhang, F.; Huang, J. Self-filtered narrowband perovskite photodetectors with ultrafast and tuned spectral response. Adv. Optical Mater. 2017, 1700672. (19) Liang, F. -X.; Wang, J. -Z.; Zhang, Z. -X.; Wang, Y.-Y.; Gao, Y.; Luo, L. -B. Broadband, ultrafast, self-driven photodetector based on Cs-doped FAPbI3 perovskite thin film. Adv. Optical Mater.2017, 5, 1700654. (20) Lian, Z.; Yan, Q.; Lv, Q.; Wang, Y.; Liu, L.; Zhang, L.; Pan, S.; Li, Q.; Wang, L.; Sun, J. – L. High-performance planar-type photodetector on (100) facet of MAPbI3 single crystal. Sci. Rep. 2015, 5, 16563. (21) Ding, J.; Fang, H.; Li, J.; Lian, Z.; Lv, Q.; Wang, L.; Sun, J. -L.; Yan, Q. A self-powered

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photodetector based on a CH3NH3PbI3 single crystal with asymmetric electrodes. CrystEngComm 2016, 18, 4405-4411. (22) Bao, C.; Chen, Z.; Fang, Y.; Wei, H.; Deng, Y.; Xiao, X.; Li, L.; Huang, J. Low-noise and large-linear-dynamic-range photodetectors based on hybrid-perovskite thin-single-crystals. Adv. Mater. 2017, 29, 1703209. (23) Deng, H.; Yang, X.; Dong, D.; Li, B.; Yang, D.; Yuan, S.; Qiao, K.; Cheng, Y. -B.; Tang, J.; Song, H. Flexible and semitransparent organolead triiodide perovskite network photodetector arrays with high stability. Nano Lett. 2015, 15, 7963. (24) a) Liu, Y.; Zhang, Y.; Yang, Z.; Yang, D.; Ren, X.; Pang, L.; Liu, S. (F.) Thinness-and shape-controlled growth for ultrathin single-crystalline perovskite wafers for mass production of superior photoelectronic devices. Adv. Mater. 2016, 28, 9204-9209. b) Y. Liu, J. Sun, Z. Yang, D. Yang, X. Ren, H. Xu, Z. Yang, S. (F.) Liu, 20-mm-Large singlecrystalline

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photodetectors. Adv. Optical Mater. 2016, 4, 1829-1837. c) Liu Y.; Ren X.; Zhang J.; Yang Z.; Yang D.; Yu F.; Sun J.; Zhao C.; Yao Z.; Wang B.; Wei Q.; Xiao F.; Fan H.; Deng H.; Deng L.; Liu S. F. 120 mm single-crystalline perovskite and wafers: towards viable applications. Sci. China Chem. 2017, 60, 1367-1376. (25) Saidaminov M. I.; Haque Md. A.; Savoie M.; Abdelhady A. L.; Cho N.; Dursun I.; Buttner U.; Alarousu E.; Wu T.; Bakr O. M. Perovskite photodetectors operating in both narrowband and broadband regimes. Adv. Mater. 2016, 28, 8144-8149. (26) Dang, Y.; Liu, Y.; Sun, Y.; Yuan, D.; Liu, X.; Lu, W.; Liu, G.; Xia, H.; Tao, X. Bulk crystal growth of hybrid perovskite material CH3NH3PbI3. CrystEngComm 2015, 17, 665-670. (27) Sarritzu, V.; Sestu, N.; Marongiu, D.; Chang, X.; Wang, Q.; Loi, M. A.; Quochi, F.; Saba,

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M.; Mura, A.; Bongiovanni, G.; Perovskite excitonics: primary exciton creation and crossover from free carriers to a secondary exciton phase. Adv. Opt. Mater. 2018, 6, 1700839. (28) Fang, Y.; Wei, H.; Dong, Q.; Huang, J. Quantification of re-absorption and re-emission processes to determine photon recycling efficiency in perovskite single crystals. Nat. Commun. 2017, 8, 14417.

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Figure 1. a) Schematic illustration of a PD array on the (100) facet of CH3NH3PbI3 single crystal. The yellow areas reprent gold electrodes. A beam focusing on one PD is highlighted with green color. b) Photoresponse of the pixel 1 under 25 cycles of 532 nm illumination. c) R for pixel 1 under 532 nm laser illumination with different intensities. d) EQE for pixel 1 from 375 nm to 808 nm illumination. 587x515mm (96 x 96 DPI)

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Figure 2. Photoresponse of the pixel 1 under relatively low frequency: a) 500 Hz, b) 3000 Hz, c) 4000 Hz, d) 5000 Hz. 689x544mm (96 x 96 DPI)

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Figure 3. Photoresponse of the pixel 1 under relatively high frequency: a) 30 KHz, b) 1 MHz, c) 80 MHz. 809x272mm (96 x 96 DPI)

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Figure 4. Photoresponse of the CH3NH3PbI3 single crystal PD array at 532 nm under different irradiance power density. a) 0.256, b) 8.823, c) 21.71, d) 80.72, e) 267.5 mW/cm2. f) R' with different irradiance power density for 4 different pixels. 812x508mm (96 x 96 DPI)

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Figure 5. a) Illustration of speed measurement based on a CH3NH3PbI3 single crystal PD array. Photoresponse of pixel 1 and pixel 2 to a moving shelter under b) 100 Hz, c) 1000 Hz, d) 3000 Hz, e) 5000 Hz. 812x561mm (96 x 96 DPI)

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Figure 6. Photoresponse of pixel 1 and pixel 2 to a moving shelter under a) 100 Hz, b) 1000 Hz, c) 3000 Hz, d) 5000 Hz after 5 months. e) Measureed photoresponse time delay between pixel 1 and pixel 2 before and after stored 5 months. f) A comparison of the calculated and tested blade shelter’s speed. 810x522mm (96 x 96 DPI)

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Figure 7. (a) Expanding light to cover the whole PD array. (b) Photoresponse of the PD array corresponding to a. (c) Small shelter moves from spot A to spot B slowly. (d) Photoresponse of the PD array corresponding to c. (e) Large shelter moves from spot A to Spot B fast. (f) Photoresponse of the PD array corresponding to e. (g) Large shelter moves from spot A to spot B with an angle. (h) Photoresponse of the PD array corresponding to g. Dashed lines stand for the moving trajectory. 808x409mm (96 x 96 DPI)

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