In the format provided by the authors and unedited. DOI: 1.138/NMAT4927 Dopant Compensation in Alloyed CH 3 NH 3 PbBr 3-x Cl x Perovskite Single Crystals for Gamma-ray Spectroscopy Haotong Wei 1, Dylan DeSantis 2, Wei Wei 1, Yehao Deng 1, Dengyang Guo 3, Tom J. Savenije 3, Lei Cao 2 and Jinsong Huang 1,4 1 Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA. 2 Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 4321, USA. 3 Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, 2628 BL Delft, The Netherlands 4 Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC 27599, USA. Characterization of the material structure and external quantum efficiency (EQE) Powder XRD measurements of CH 3 NH 3 PbBr 3-x Cl x single crystal were performed with a Bruker-AXS D8 Discover X-ray diffractometer with Vantec 5 Area Detector, and a conventional copper target. The measurement error is within 5%. The EQE was measured with the Newport QE measurement kit by focusing monochromatic beam of light onto the devices. The incident light was chopped at 35 Hz, and the optical power density was controlled to be around 1 µw/cm 2. A Si diode which had calibrated response from 28 nm to 11 nm was used E-mail: jhuang2@unl.edu 1 NATURE MATERIALS www.nature.com/naturematerials 1 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 to calibrate the light intensity for photocurrent measurement. The measurement error is within.2% Hole and electron mobilities by time of flight (ToF) method ToF measurement was conducted by illuminating the devices with 4 ns width, 337 nm laser pulses (SRS N 2 laser) from the semitransparent electrodes. The pulse laser generated photocurrent was recorded using an Agilent 1 GHz digital oscilloscope (Agilent DSO-X 314A). For hole mobility measurement, laser was illuminated from semi-transparent cathode. The photogenerated electrons were collected by the cathode immediately, and the photogenerated holes traveled through the CH 3 NH 3 PbBr 3-x Cl x single crystals under applied field until reaching the other electrode. The Schottky junction effectively prevented charge injection under reverse electric field, which allowed clear ToF signals to be extracted and recorded. The hole mobility was calculated from the equation (s1). tt "#$%&'" "')* =,-./ (s1) where d is thickness of the single crystals, V is the applied voltage, µ is the charge carriers mobility and t is the transit time of the charge carriers. Due to the dispersive transport property of carriers in the single crystals, the charge transit time was determined from the intercept of the pre-transit and post-transit asymptotes of the photocurrent on a double-logarithmic scale plot as shown in Figure S1. For electron mobility measurement, laser was illuminated from the anode side and the photogenerated electrons traveled through the CH 3 NH 3 PbBr 3-x Cl x single crystals under applied electrical field until reaching the other electrode. The measurement error is within 5% NATURE MATERIALS www.nature.com/naturematerials 2 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Hall effect measurement Hall effect measurement was conducted on single crystals with the size of 3 mm 3 mm 2 mm in dark. All four electrodes are gallium. A Keithley 24 source meter was used to apply DC current and a Keithley 42 source meter was used to record the Hall voltage. The majority carrier was determined to be holes or electrons based on the Hall voltage sign. The schematic of set up of the Hall effect measurement is shown below in Scheme S1. Scheme S1. Hall effect measurement setup for CH 3 NH 3 PbBr 3-x Cl x single crystals Photoconductivity of the CH 3 NH 3 PbBr 3-x Cl x single crystals Photoconductivity measurement was carried out on the CH 3 NH 3 PbBr 3-x Cl x single crystals device with a thickness of 3.5 mm, and a device area of 3~5 mm 2. Excitation light from a 39 nm LED, modulated at 35 Hz by a function generator, was illuminated on the cathode of the device. Different reverse voltage was supplied by a Keithley 24 source-meter (5 pa measurement error), and photocurrent was recorded by a SR-83 lock-in amplifier. A fitting of the observed photocurrent versus reverse voltage using modified Hecht equation (s2) yields both µτ product and s. The µτ product reflects the crystal bulk electronic property, and it is proportional to the charge carrier diffusion length, while s presents the surface recombination velocity which directly affects the charge collection efficiency. 3 NATURE MATERIALS www.nature.com/naturematerials 3 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 II = 1 2.3/ ; 56789 (6 - <=> ) 4-5@ ; A > < (s2) where I is the saturated photocurrent, L is the thickness, and V is the applied voltage. The measurement error is within 2% Trap density of CH 3 NH 3 PbBr 3-x Cl x single crystals Trap density was measured by thermal admittance spectroscopy (TAS). The experiments were performed by using an Agilent E498A Precision LCR Meter with frequencies between.1 to 1 khz. The energy profile of trap density of states (tdos) was derived from the angular frequency dependent capacitance with the equation (s3). NN C EE E = / GH,K E IJ,E L M C (s3) where C is the capacitance, ω is the angular frequency, q is the elementary charge, k B is the Boltzmann constant and T is the temperature. V bi and W are the built-in potential and depletion width, respectively, which were extracted from the Mott-Schottky analysis. The applied angular frequency ω defines an energetic demarcation. EE E = kk O TTTTTT( E 2 E ), where ω is the attempt-to-escape frequency. The measurement error is within 2% Noise, NEP and D * of CH 3 NH 3 PbBr 3-x Cl x single crystals Noise current was carried out at different frequency by a Fast Fourier Transform (FFT) signal analyzer (Agilent 3567A) which was connected to a low noise current preamplifier, and noise equivalent power (NEP) was directly measured in the same way as noise current but illuminating a modulated light on the device with gradually attenuated light intensity. Specific detectivity (D * ) is calculated according to equation (s4). 4 NATURE MATERIALS www.nature.com/naturematerials 4 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 DD = (UO)V - WXY (s4) where A is the device area, B is the bandwidth, NEP is the noise equivalent power. The measurement error is within 2% Guard ring electrode deposition The guard ring electrode was deposited by thermal evaporation together with the central cathode. A copper wire with diameter of 5 µm was stick on the single crystal as mask to separate the guard electrode with central cathode. An actual photo of device with guard ring electrode is shown in Figure S9. Compton scattering in 137 Cs energy spectrum In addition to the full energy photoelectric absorption, photons scattering is another frequent event as shown in the linear attenuation coefficients of CH 3 NH 3 PbBr 2.94 Cl.6 in Figure 5d. Scattered photons energy can be calculated by Compton scattering equation: 5 5 = 5 (1 cos θθ) (s5) X V X 2 ) Z [- where E and E 1 are the energy of incident and scattered photons, respectively. m e is the electron mass, c is the light speed and θ is the angle between scattered photon and incident photon. Scattered photons energy is directly determined by the incident photons energy and the scattered angle. Compton edge energy E e can be derived by E e =662 (kev)-e 1 when θ is -18 o, and E e is calculated to be 478 kev according to the equation which is in accordance with our result. Commercial price estimation of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal NATURE MATERIALS www.nature.com/naturematerials 5 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 We estimated the raw material cost of CH 3 NH 3 PbBr 2.94 Cl.6 single crystals based on the prices of PbBr 2, CH 3 NH 3 Br and CH 3 NH 3 Cl listed in the Sigma-Aldrich or other suppliers where current purchase the raw materials from. The price of PbBr 2 (98% grade) is in the range of $.7-1./g, the price of CH 3 NH 3 Br is in the range of $.8-$1./g, and the price of CH 3 NH 3 Cl is in the range of $.1-$.2/g. The density of CH 3 NH 3 PbBr 2.94 Cl.6 single crystals is about 3.7 g/cm 3, and 1 cm 3 CH 3 NH 3 PbBr 2.94 Cl.6 single crystal needs PbBr 2 2.83 g, corresponding to $2.-$2.8; CH 3 NH 3 Br.85 g, corresponding to $.65~$.85; and CH 3 NH 3 Cl.3 g, corresponding to $.3~.6. Therefore the total material cost for 1 cm 3 CH 3 NH 3 PbBr 2.94 Cl.6 single crystal is about $2.65-$3.65. Considering the material cost generally reduce by 5-1 times after scaling up the production, we estimate the material cost of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal is less than $.3/cm 3. a b c J (ma cm -2 ) 1-4 1-5 1-6 1-7 J (ma cm -2 ) 1-3 1-4 1-5 IQE (%) 1 2 1 1 1-8 -5-4 -3-2 -1 1 2 3 4 5 Voltage (V) -5-4 -3-2 -1 1 2 3 4 5 Voltage (V) 1 4 45 5 55 6 Wavelength (nm) Figure S1 Reproducibility of four CH 3 NH 3 PbBr 2.94 Cl.6 single crystal Device. a, dark current density of four CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device. b, photocurrent density of four CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device. c, IQE spectrum of four CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device. NATURE MATERIALS www.nature.com/naturematerials 6 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Figure S1 shows the good reproducibility of dark current density, photocurrent density and IQE spectrum of four CH 3 NH 3 PbBr 2.94 Cl.6 Single Crystal Device. a b c 1 1-1 1-2 1 1-1 1-2 4 3 2 1 =22 cm 2 V -1 s -1 d=2.63 mm..3.6.9-1v -2V -3V 1 1 1 µ e =1 cm 2 V -1 s -1 d=2.2 mm 24 18 12 6..1.2.3.4.5-2V -3V -4V 1 1 1 d e f 1 1-1 1 1-1 1-2 =56 cm 2 V -1 s -1 d=3. mm 15 1 5..2.4.6.8 1. 1 1 µ e =34 cm 2 V -1 s -1 d=2.62 mm 25 2 15 1 5..3.6.9-1.V -1.5V -1V -2V -3V 1 1 1 1 1-1 1-2 1-3 1 1-1 1-2 =439 cm 2 V -1 s -1 d=3.39 mm 36 27 18 9..3.6.9 1.2 -.8V -1.6V -2.4V 1 1 1 3 2 1 µ e =332 cm 2 V -1 s -1 d=4.2 mm..1.2.3.4.5 1 1 1-2V -4V Figure S2 Hole and electron mobility of CH 3 NH 3 PbBr 3-x Cl x single crystals with different Cl amount. Hole mobility of CH 3 NH 3 PbBr 3-x Cl x single crystals with a, % Cl b, 2.% Cl and c, 5.1% Cl doping as well as electron mobility of CH 3 NH 3 PbBr 3-x Cl x single crystals with d, % Cl e, 2.% Cl and f, 5.1% Cl doping by ToF technique. Fig. S2 shows that the CH 3 NH 3 PbBr 3-x Cl x single crystals with 2.% Cl doping has the champion hole mobility of over 5 cm 2 V -1 s -1 compared to the CH 3 NH 3 PbBr 3-x Cl x single crystals with % and 5.1 % Cl doping. Electron mobility follows the same trend. 7 NATURE MATERIALS www.nature.com/naturematerials 7 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 a 8 CH 3 NH 3 PbBr 3 b 6 Percentage (%) 6 4 2 CH 3 NH 3 PbBr 2.94 Cl.6 CH 3 NH 3 PbBr 2.85 Cl.15 Percentage (%) 4 2 c 6 2 3 4 5 6 Hole Mobility (cm 2 V -1 s -1 ) d.5.1.15.2.25 µτ product (cm 2 V -1 ) 6 Percentage (%) 4 2 Percentage (%) 4 2 1 9 1 1 Resistivity (Ω cm) 1 6 1 7 1 8 Charge Carrier Concentration(cm -3 ) Figure S3 Statistic distribution of electric properties of CH 3 NH 3 PbBr 3-x Cl x. a, Statistic distribution of hole mobility of CH 3 NH 3 PbBr 3, CH 3 NH 3 PbBr 2.94 Cl.6 and CH 3 NH 3 PbBr 2.85 Cl.15 single crystals. b, Statistic distribution of µτ product of CH 3 NH 3 PbBr 3, CH 3 NH 3 PbBr 2.94 Cl.6 and CH 3 NH 3 PbBr 2.85 Cl.15 single crystals. c, Statistic distribution of resistivity of CH 3 NH 3 PbBr 3, CH 3 NH 3 PbBr 2.94 Cl.6 and CH 3 NH 3 PbBr 2.85 Cl.15 single crystals. d, Statistic distribution of charge carrier concentration of CH 3 NH 3 PbBr 3, CH 3 NH 3 PbBr 2.94 Cl.6 and CH 3 NH 3 PbBr 2.85 Cl.15 single crystals. NATURE MATERIALS www.nature.com/naturematerials 8 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Figure S4 The electron mobility of CH 3 NH 3 PbBr 3-x Cl x single crystals with different Cl amount. Electron mobility of CH 3 NH 3 PbBr 3-x Cl x single crystals with a, % Cl b, 2.% Cl and c, 5.1% Cl doping by using Space-Charges-Limited-Current (SCLC) method. We verified the ToF result by using SCLC method with electron-only device structure of Au/BCP/C 6 /CH 3 NH 3 PbBr 3-x Cl x /C 6 /BCP/Au. Fig. S4 shows the electron-only device result of CH 3 NH 3 PbBr 3-x Cl x single crystals with different Cl doping amount. Once again, CH 3 NH 3 PbBr 3-x Cl x single crystal with 2.% Cl has the highest electron mobility of 51 cm 2 V -1 s -1. NATURE MATERIALS www.nature.com/naturematerials 9 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 a =253 cm 2 V -1 s -1 b 1 1 =283 cm 2 V -1 s -1 c d=2.3 mm -1.V -2.V d=2.3 mm -1.2V -2.V 1 1 1 1 d e 1 1 µ =393 cm 2 V -1 s -1 h =338 cm 2 V -1 s -1 f d=2.3 mm -2.V d=2.3 mm -2.V 1 1-1 1 1-1 2 15 1 5..2.4.6.8 1. 2 15 1 5..1.2.3.4.5 1 1 28K 23K 1 1-1 1 1-1 2 15 1 5..2.4.6.8 1. 2 15 1 5..1.2.3.4.5 26K 2K 2 4 6 81 1 1-1 1 1 1 1-1 1 1 =311 cm 2 V -1 s -1 d=2.3 mm 2 15 1 5..1.2.3.4.5 =464 cm 2 V -1 s -1 d=2.3 mm 2 15 1 5..1.2.3.4.5-2.V 243K -2.V 18K 2 4 6 81 Figure S5 The hole mobility of CH 3 NH 3 PbBr 3 single crystals as temperature. Hole mobility by ToF technique of CH 3 NH 3 PbBr 3 single crystals device at a, 28K. b, 26K. c, 243K. d, 23K. e, 2K and f, 18K. 1 NATURE MATERIALS www.nature.com/naturematerials 1 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 a b c d g 1 1-1 1 1 1-1 1 1 =8 cm 2 V -1 s -1 d=3. mm 6 4 2 =56 cm 2 V -1 s -1 d=3. mm 15 1 5..2.4.6.8 1...2.4.6-1.V -1.5V 31K -2.V 243K 2 4 6 81 =119 cm 2 V -1 s -1 d=3. mm 4 3 2 1-1 -.2..2.4.6-3.V 18K 2 4 6 81 e 1 1-1 =62 cm 2 V -1 s -1 d=3. mm 6 3..2.4.6 1 1 1 1 =86 cm 2 V -1 s -1 d=3. mm 1 1-1 9 6 3..1.2.3.4.5-2V -3V 28K -3.V 23K 2 4 6 81 f 1 1-1 1-1 =75 cm 2 V -1 s -1 d=3. mm 8 6 4 2..2.4.6 1 5..1.2.3.4.5-2.V 26K 1 1 1 1 =1 cm 2 V -1 s -1 d=3. mm -2.V -3.V 2K 1 2 4 6 81 Figure S6 The hole mobility of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal as temperature. Hole mobility by ToF technique of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device at a, 31K. b, 28K. c, 26K. d, 243K. e, 23K. f, 2K and g, 18K. NATURE MATERIALS www.nature.com/naturematerials 11 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 a d g 1 1-1..2.4.6.8 1-2 1 1 =625 cm 2 V -1 s -1 d=3.74 mm -1.5V 1-2.V 1-1 1-2 1 1-1 1-2 2 1 2 15 1 5..2.4.6.8 1. 1 1 =456 cm 2 V -1 s -1 d=3.74 mm =92 cm 2 V -1 s -1 d=3.74 mm 16 12 8 4..2.4.6.8 1. 1.2 1 1-1.5V -2.V 31K 243K -1.V -1.5V -2.V 18K b e 1 1-1 1-2 =491 cm 2 V -1 s -1 d=3.74 mm 3 2 1..2.4.6.8 1. 1 1 =68 cm 2 V -1 s -1 1 d=3.74 mm 1-1 1-2 15 1 5..2.4.6.8 1 1-1.V -1.5V -2.V 28K -1.5V -2.V 23K c f 1 1-1 1-2 1 1-1 3 2 1 =556 cm 2 V -1 s -1 d=3.74 mm..2.4.6.8 1. 1 1 =744 cm 2 V -1 s -1 d=3.74 mm 2 15 1 5..2.4.6.8 1 1-1.V -1.5V -2.V 26K -1.5V -2.V 2K Figure S7 The hole mobility of CH 3 NH 3 PbBr 2.85 Cl.15 single crystal as temperature. Hole mobility by ToF technique of CH 3 NH 3 PbBr 2.85 Cl.15 single crystal device at a, 31K. b, 28K. c, 26K. d, 243K. e, 23K. f, 2K and g, 18K. NATURE MATERIALS www.nature.com/naturematerials 12 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Table S1. Calculated charge carrier concentration. CH 3 NH 3 Pb Br 3 CH 3 NH 3 Pb Br 2.94 Cl.6 CH 3 NH 3 Pb Br 2.85 Cl.15 CH 3 NH 3 Pb Br 2.4 Cl.6 CH 3 NH 3 Pb Cl 3 Charge carrier type p p or n n n n Hole Mobility [a] (cm 2 V -1 s -1 ) Electron Mobility [a] (cm 2 V -1 s -1 ) 22 56 439 116 145 14 34 318 7 62 Resistivity [b] (Ω cm) 7.1 1 8 3.6 1 9 1.8 1 9 2.5 1 8 1.5 1 8 Charge carrier concentration (cm -3 ) 4. 1 7 3.1 1 6 1.1 1 7 3.6 1 8 6.7 1 8 [a] Mobility is measured by ToF technique [b] Resistivity is derived from devices with guard ring electrode The charge carrier concentration n is determined by n=1/(r µ e) as shown in Table S1, where R is the resistivity, µ is the mobility and e is the elementary charge. Since the resistivity here excludes the surface leakage current, the charge carrier concentration here is the bulk property, and the average charge carrier concentration of the single crystal should be higher than this. NATURE MATERIALS www.nature.com/naturematerials 13 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Figure S8 Sensitivity to 8 kev X ray. a, Current density output to 8 kev X-rays with dose rate of 2.4 µgy air s -1 and noise current density of 1 mm thick CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device as applied voltage. b, Current density output of 1 mm thick CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device to 8 kev X-rays with different dose rate. A sensitivity of 84 µc Gy -1 air cm -2 is derived from the slope of the fitting line. Figure S8a shows the photocurrent signal and noise current versus applied voltage, and there is a sharp increase of noise when applied voltage is increased from 6V to 7V. We thus used 6 V as working voltage and obtained a sensitivity of 84 µc Gy -1 air cm -2 to 8 kev X-rays with lowest detectable dose rate of 7.6 ngy air s -1 as shown in Figure S8b. 14 NATURE MATERIALS www.nature.com/naturematerials 14 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 Figure S9 a, Linear attenuation coefficients of CH 3 NH 3 PbBr 2.94 Cl.6 perovskite versus different photon energy. b, Reproducibility study of 137 Cs energy spectrum by two CH 3 NH 3 PbBr 2.94 Cl.6 single crystals (Red: device I and blue: device III). Figure S9a shows the Linear attenuation coefficients of CH 3 NH 3 PbBr 2.94 Cl.6 perovskite versus different photon energy. Figure S9b shows the reproducibility of the 137 Cs energy spectrum by another two CH 3 NH 3 PbBr 2.94 Cl.6 single crystals. Three big single crystals in centimeter scale are grown and fabricated into devices, and all of them are able to acquire the 137 Cs energy spectrum with all features observed. The resolutions of device I, II and III are 15.4%, 6.5% to 12.7%, respectively. 15 NATURE MATERIALS www.nature.com/naturematerials 15 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
DOI: 1.138/NMAT4927 a b 1-4 IQE (%) 1 2 1 1 1 As synthesized Storage in air for one month 4 45 5 55 6 Wavelength (nm) J (ma cm -2 ) 1-5 1-6 1-7 1-8 -5-4 -3-2 -1 1 2 3 4 5 Voltage (V) Figure S1 Stability study of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device. a, IQE spectra of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal as synthesized and stored in air for one month. b, dark current of CH 3 NH 3 PbBr 2.94 Cl.6 single crystal as synthesized and stored in air for one month. Figure S1 shows the good shelf stability of the CH 3 NH 3 PbBr 2.94 Cl.6 single crystal device. There is almost no change of the IQE spectra and dark current after one-month storage in air as a detector. NATURE MATERIALS www.nature.com/naturematerials 16 217 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.