Thermally Stable Silver Nanowires-embedding. Metal Oxide for Schottky Junction Solar Cells

Transcription

1 Supporting Information Thermally Stable Silver Nanowires-embedding Metal Oxide for Schottky Junction Solar Cells Hong-Sik Kim, 1 Malkeshkumar Patel, 1 Hyeong-Ho Park, Abhijit Ray, Chaehwan Jeong, # and Joondong Kim, * Photoelectric and Energy Device Application Lab (PEDAL) and Department of Electrical Engineering, Incheon National University, 119 Academy Rd. Yeonsu, Incheon, 46772, Republic of Korea Applied Device and Material Lab., Device Technology Division, Korea Advanced Nano Fab Center (KANC), Suwon 44327, Republic of Korea Solar Research and Development Center, Pandit Deendayal Petroleum University, Gandhinagar 3827, Gujarat, India # Applied Optics and Energy Research Group, Korea Institute of Industrial Technology, Gwangju 548, Republic of Korea * addresses: joonkim@incheon.ac.kr S-1

2 Experimental description: A simulator system (McScience-K3, Korea) was employed to measure solar cell performances. A photovoltaic power meter (McScience-K11) was used to monitor the I V characteristics under one sun (1 mw cm -2 ) illumination. Light intensity was calibrated with standard Si photodiode at room temperature. Al front grid with dimension 1 mm x 1 mm were used and connected to the negative terminal of the source measure unit coupled with sun simulator. The intensity distribution profile as a function of photon wavelength is calibrated using standard Si photodiode and shown in Figure 1. After the calibration of power density, quantum efficiency was recorded. The junction of the device was isolated using diamond stylus after the depositing the front Al grid. This area of the device was fixed approximately 1 mm 2 + 5% (error). Carrier collection efficiencies of solar cells were profiled using a quantum efficiency measurement system (McScience-K31, Korea) coupled with monochromatic (Oriel Cornerstone 13 1/8 m Monochromator), source measurement unit (244, Keithley) and lock in amplifier (K12, McScience). Mott-Schottky analyses (C-V characteristics) and impedance spectra of the Schottky junction devices were obtained by using the Potentiostat/Galvanostat (ZIVE SP1, WonA Tech, Korea). The Potentiostat/Galvanostat was calibrated with a standard static and dynamic circuit before the impedance and Mott-Schottky measurement. The high temperature stability was studied by vacuum compatible probe station under the monochromatic illumination coupled with temperature controller (TC-2P, Misung Scientific), digital oscilloscope (TBS 112B-EDU, Tektronix), and function generator (MFG-313A, MCH Instruments). The high temperature and monochromatic excitation setup is shown in Figure 2, used for obtaining device performances. S-2

3 1 2 3 Figure S1. Photographs of developed various Schottky junction solar cells, 1-AgNWs/p-Si, 2ITO/p-Si, and 3-ITO/AgNWs/ITO/p-Si. a ITO surface b p-si Figure S2. SEM images of AgNWs dispersed on different surfaces, (a) on ITO-coated Si substrate, and (b) Si substrate. Figure S3. SEM images of AgNWs-embedding ITO layers. S-3

4 22 22 AgNW AgNW Tear drop ITO Tear drop ITO Figure S4. Electron diffraction patterns of the one dimensional AgNWs and ITO films. Transmission electron microscopy analysis shows that the AgNWs are single crystals that grow along the [11] direction with pentagonal {111} twin planes running down the entire wire length (The selected area electron diffraction pattern of 22 shows excellent texture of [111] zone axis.). S-4

5 Current density (ma cm -2 ) 1E+1 1E+ 1E-1 1E-2 1E-3 After RTP Before RTP 1E-4 1E Voltage (V) Figure S5. Dark J-V characteristics of AgNWs embedded ITO-p-Si Schottky junction solar cells at room temperature. The diode ideality factor was estimated by following relation, Ғ= ( ) where KT and q are the thermal energy and electron charge, respectively. Rectification ratio of the device was calculated by taking the ratio of the current density at -1 V and +1 V as shown in the Figure S5. Table S1. Estimated diode parameter from the J-V characteristics. Condition Saturation current density, J o (ma cm -2 ) Diode parameter Rectification ratio, RR Ideality factor, Ғ Before RTP After RTP S-5

6 Figure S6. Mott-Schottky characteristics of AgNW/p-Si device, measured under dark condition. Figure S7. Proposed equivalent circuit for the developed Schottky junction solar cell. S-6

7 a -Z" (ohms) 2k 15k 1k 5k -.8 V -.7 V -.6 V -.5 V -.4 V -.3 V -.2 V -.1 V 1 mv 1k 2k 3k Z' (ohms) b -Z" (ohms) 2.5x1 3 2.x x1 3 1.x1 3 5.x x1 3 2x1 3 3x1 3 4x1 3 Z' (ohms).1 V.2 V.3 V.4 V.5 V.6 V.7 V Figure S8. Biased Impedance spectra for the Schottky junction solar cell at room temperature. (a) Revers bias and (b) forward bias conditions. S-7

8 Voltage (V) On λ = 85 nm, 8 mw cm -2 Off (t) = V O + A 1 e -t-t /τ o V O =.74 mv A 1 =.6 τ =.155 ms 5m 1m time (s) Figure S9. Open circuit voltage decay of Schottky junction solar cell to estimate the minority carrier life time. Device was illuminated using monochromatic light of 85 nm with intensity 8 mw cm -2. The decay profile was fitted using the relation (t) = V O + A 1 e -t-to/τ, where V o, A 1, t, and τ are baseline voltage, constant, time and minority carrier life time, respectively K 38 K 313 K 323 K 333 K 343 K 353 K 363 K 373 K 383 K 393 K 43 K 413 K 423 K 433 K 438 K 443 K Figure S1. Open circuit voltage decay profiles at various device operational temperature from room temperature (35 K to 443 K). Excitation wavelength 85 nm and intensity 2 mw cm -2. S-8

9 K τ =.228 ms K τ =.211 ms K τ =.151 ms K τ =.13 ms K τ = 92 µs K τ = 83 µs K K 2 43 K τ = 74 µs τ = 7 µs τ = 75 µs K K K 1 5 τ = 7 µs 5 τ = 55.4 µs 5 25 τ = 53 µs Figure S11. Open circuit voltage decay characteristics of AgNWs embedded ITO-p-Si Schottky junction solar cell as a function of high operational temperature. S-9

10 Efficiency, η (%) η J SC FF temperature (K) Current density, J SC (ma cm -2 ) Fill factor (%) temperature (K) τ Carrier life time, τ (ms) Figure S12. Solar cell performance parameter and their temperature dependence. Excitation wavelength 85 nm and intensity 2 mw cm -2. The carrier life time was estimated by fitting the voltage decay profiles acquired at various device operational temperature and are shown in the Figure S11 and S12. Device statistics in tables/plots as well as detailed experimental description (Figure S13- S2, table S2) x1-8 Intensity (W m -2 ) 1.x1-8 5.x Wavelength, λ (nm) Figure S13, Intensity distribution as a function of photon wavelength, which used for quantum efficiency measurement. S-1

11 . Figure S14. Device under test, for high temperature current voltage characteristics including the monochromatic excitation (85 nm). Table S2. Device statistics. All device measured at room temperature. Sample code Description J SC (ma cm -2 ) FF (%) Efficiency, η (%) AgNW/p-Si As prepared AgNW/p-Si After RTP Break down, open circuit AgNWs-capped- ITO/p-Si As prepared AgNWs-capped- ITO/p-Si Thermally treated RTP, 5 (1 minute) O C AgNWs-capped- ITO/p-Si Thermally treated O C RTP, 5 (1 minute) 2 mw cm -2, 85 nm S-11

12 a Current density (ma cm -2 ) AgNWs/p-Si dark AM1.5 b Current density (ma cm -2 ) AgNWs/p-Si = 52 mv J SC = 14.8 ma cm -2 FF = 27.1% η = 2.1% AM Voltage (V)..2.4 Voltage (V) Figure S15. Current-voltage characteristics of AgNW/p-Si devices. (a) dark and AM 1.5, (b) 4 th quadrant with estimated solar cell parameters. Quantum efficiency (%) External QE Internal QE Reflectance Wavelength, λ (nm) Reflectance (%) Figure S16. Quantum efficiency of AgNW-capped ITO/p-Si device including the reflectance profile. S-12

13 Quantum efficiency (%) IQE EQE Reflectance AgNW/p-Si devices Wavelength (nm) Figure S17. Quantum efficiency and reflectance of AgNW/p-Si devices. Current density (ma cm -2 ) Voltage (V) dark.5 mw/cm2 3 mw/cm2 8 mw/cm2 14 mw/cm2 19 mw/cm mw/cm mw/cm mw/cm2 38 mw/cm mw/cm2 5 mw/cm2 55 mw/cm2 62 mw/cm2 68 mw/cm mw/cm2 79 mw/cm2 85 mw/cm mw/cm2 95 mw/cm mw/cm2 11 mw/cm2 Figure S18. Effect of light intensity dependent J-V characteristic measured using AgNW-capped ITO/p- Si device. S-13

14 J SC (ma cm -2 ) Jsc (ma cm-2) VOC (V) (V) Light intensity (ma cm -2 ) Figure S19. J SC and as a function of applied light intensity for AgNW-capped ITO/p-Si device. 8 eta FF 7 Efficiency (%) Fill factor (%) Light intensity (mw cm -2 ) Figure S2. Efficiency and FF as a function of applied light intensity for AgNW-capped ITO/p-Si device. REFERENCES (1) A Checklist for Photovoltaic Research. Nat. Mater. 215, 14 (November), 173. S-14