Current Optics and Photonics

Optical Society of Korea (한국광학회)
권호 표지
DOI QR코드

DOI QR Code

Direct Measurement of Diffusion Length in Mixed Lead-halide Perovskite Films Using Scanning Photocurrent Microscopy

  • Kim, Ahram (Department of Physics and Department of Energy Systems Research, Ajou University) ;
  • Son, Byung Hee (Department of Physics and Department of Energy Systems Research, Ajou University) ;
  • Kim, Hwan Sik (Department of Physics and Department of Energy Systems Research, Ajou University) ;
  • Ahn, Yeong Hwan (Department of Physics and Department of Energy Systems Research, Ajou University)
  • Received : 2018.10.08
  • Accepted : 2018.11.07
  • Published : 2018.12.25
Download PDF
⟨ Previous Next ⟩

Abstract

Carrier diffusion length in the light-sensitive material is one of the key elements in improving the light-current conversion efficiency of solar-cell devices. In this paper, we measured the carrier diffusion length in lead-halide perovskite ($MAPbI_3$) and mixed lead-halide ($MAPbI_{3-x}Cl_x$) perovskite devices using scanning photocurrent microscopy (SPCM). The SPCM signal decreased as we moved the focused laser spot away from the metal contact. By fitting the data with a simple exponential curve, we extracted the carrier diffusion length of each perovskite film. Importantly, the diffusion length of the mixed-halide perovskite was higher than that of the halide perovskite film by a factor of 3 to 6; this is consistent with the general expectation that the carrier mobility will be higher in the case of the mixed lead-halide perovskites. Finally, the diffusion length was investigated as a function of applied bias for both samples, and analyzed successfully in terms of the drift-diffusion model.

Keywords

KGHHD@_2018_v2n6_514_f0001.png 이미지

FIG. 1. (a) Schematic diagram of a perovskite device with drain and source electrodes embedded in a quartz substrate. For the diffusion-length measurement, we used a SPCM technique with a focused 532-nm laser. SEM images of (b) lead-halide and (c) mixed lead-halide perovskite films respectively.

KGHHD@_2018_v2n6_514_f0002.png 이미지

FIG. 2. (a) ISPCM image of lead-halide perovskite film with a channel length of 30 μm. (b) Line profile of ISPCM as a function of position along the channel, extracted from (a).

KGHHD@_2018_v2n6_514_f0003.png 이미지

FIG. 3. (a) Two-dimensional plot of ISPCM as a function of position (x-axis) and VDS (y-axis) for a MAPbI3-xClx device with channel length of 20 μm. (b) Line profiles of ISPCM as a function of position, extracted from (a) for different values of VDS.

KGHHD@_2018_v2n6_514_f0004.png 이미지

FIG. 4. (a) Semilogarithmic plots of ISPCM as a function of position for different values of VDS. (b) Diffusion length as a function of VDS, for both MAPbI3-xClx (filled boxes) and MAPbI3 (open circles) devices with channel length of 20 μm. Solid lines are fits to the data based on the drift-diffusion model.

References

  1. L. M. Herz, "Charge-carrier mobilities in metal halide perovskites: fundamental mechanisms and limits," ACS Energy Lett. 2, 1539-1548 (2017). https://doi.org/10.1021/acsenergylett.7b00276
  2. S. D. Stranks, G. E. Eperon, G. Grancini, C. Menelaou, M. J. P. Alcocer, T. Leijtens, L. M. Herz, A. Petrozza, and H. J. Snaith, "Electron-hole diffusion lengths exceeding 1 micrometer in an organometal trihalide perovskite absorber," Science 342, 341-344 (2013). https://doi.org/10.1126/science.1243982
  3. Q. Dong, Y. Fang, Y. Shao, P. Mulligan, J. Qiu, L. Cao, and J. Huang, "Electron-hole diffusion lengths >175 ${\mu}$m in solution-grown $CH_3NH_3PbI_3$ single crystals," Science 347, 967-970 (2015). https://doi.org/10.1126/science.aaa5760
  4. H. J. Snaith, "Perovskites: The emergence of a new era for low-cost, high-efficiency solar cells," J. Phys. Chem. Lett. 4, 3623-3630 (2013). https://doi.org/10.1021/jz4020162
  5. M. A. Green, A. Ho-Baillie, and H. J. Snaith, "The emergence of perovskite solar cells," Nat. Photon. 8, 506-514 (2014). https://doi.org/10.1038/nphoton.2014.134
  6. C. Wehrenfennig, G. E. Eperon, M. B. Johnston, H. J. Snaith, and L. M. Herz, "High charge carrier mobilities and lifetimes in organolead trihalide perovskites," Adv. Mater. 26, 1584-1589 (2014). https://doi.org/10.1002/adma.201305172
  7. Y. Jeong, J. K. Sahu, D. N. Payne, and J. Nilsson, "Ytterbiumdoped large-core fibre laser with 1 kW of continuous-wave output power," Electron. Lett. 40, 470-472 (2004). https://doi.org/10.1049/el:20040298
  8. Y. Jeong, J. K. Sahu, D. N. Payne, and J. Nilsson, "Ytterbiumdoped large-core fiber laser with 1.36 kW continuous-wave output power," Opt. Express 12, 6088-6092 (2004). https://doi.org/10.1364/OPEX.12.006088
  9. U. Keller, "Recent developments in compact ultrafast lasers," Nature 424, 831-838 (2003). https://doi.org/10.1038/nature01938
  10. W. Nie, H. Tsai, R. Asadpour, J. C. Blancon, A. J. Neukirch, G. Gupta, J. J. Crochet, M. Chhowalla, S. Tretiak, M. A. Alam, H. L. Wang, and A. D. Mohite, "High-efficiency solution-processed perovskite solar cells with millimeter-scale grains," Science 347, 522-525 (2015). https://doi.org/10.1126/science.aaa0472
  11. G. Hodes and P. V. Kamat, "Understanding the implication of carrier diffusion length in photovoltaic cells," J. Phys. Chem. Lett. 6, 4090-4092 (2015). https://doi.org/10.1021/acs.jpclett.5b02052
  12. Y. Yamada, T. Nakamura, M. Endo, A. Wakamiya, and Y. Kanemitsu, "Photocarrier recombination dynamics in perovskite CH3NH3PbI3 for solar cell applications," J. Am. Chem. Soc. 136, 11610-11613 (2014). https://doi.org/10.1021/ja506624n
  13. V. D'Innocenzo, A. R. Srimath Kandada, M. De Bastiani, M. Gandini, and A. Petrozza, "Tuning the light emission properties by band gap engineering in hybrid lead halide perovskite," J. Am. Chem. Soc. 136, 17730-17733 (2014). https://doi.org/10.1021/ja511198f
  14. S. D. Stranks, V. M. Burlakov, T. Leijtens, J. M. Ball, A. Goriely, and H. J. Snaith, "Recombination kinetics in organic-inorganic perovskites: excitons, free charge, and subgap states," Phys. Rev. Appl. 2, 034007 (2014). https://doi.org/10.1103/PhysRevApplied.2.034007
  15. E. Alarousu, A. M. El-Zohry, J. Yin, A. A. Zhumekenov, C. Yang, E. Alhabshi, I. Gereige, A. Alsaggaf, A. V. Malko, O. M. Bakr, and O. F. Mohammed, "Ultralong radiative states in hybrid perovskite crystals: compositions for submillimeter diffusion lengths," J. Phys. Chem. Lett. 8, 4386-4390 (2017). https://doi.org/10.1021/acs.jpclett.7b01922
  16. W. Tian, C. Zhao, J. Leng, R. Cui, and S. Jin, "Visualizing carrier diffusion in individual single-crystal organolead halide perovskite nanowires and nanoplates," J. Am. Chem. Soc. 137, 12458-12461 (2015). https://doi.org/10.1021/jacs.5b08045
  17. J. K. Park, J. C. Kang, S. Y. Kim, B. H. Son, J. Y. Park, S. Lee, and Y. H. Ahn, "Diffusion length in nanoporous photoelectrodes of dye-sensitized solar cells under operating conditions measured by photocurrent microscopy," J. Phys. Chem. Lett. 3, 3632-3638 (2012). https://doi.org/10.1021/jz301751j
  18. J. D. Park, B. H. Son, J. K. Park, S. Y. Kim, J. Y. Park, S. Lee, and Y. H. Ahn, "Diffusion length in nanoporous $TiO_2$ films under above-band-gap illumination," AIP Adv. 4, 067106 (2014). https://doi.org/10.1063/1.4881875
  19. S. Liu, L. Wang, W. C. Lin, S. Sucharitakul, C. Burda, and X. P. A. Gao, "Imaging the long transport lengths of photo-generated carriers in oriented perovskite films," Nano Lett. 16, 7925-7929 (2016). https://doi.org/10.1021/acs.nanolett.6b04235
  20. N. J. Jeon, J. H. Noh, Y. C. Kim, W. S. Yang, S. Ryu, and S. I. Seok, "Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells," Nat. Mater. 13, 897-903 (2014). https://doi.org/10.1038/nmat4014
  21. J. K. Park, B. H. Son, J. Y. Park, S. Lee, and Y. H. Ahn, "High-speed scanning photocurrent imaging techniques on nanoscale devices," Curr. Appl. Phys. 13, 2076-2081 (2013). https://doi.org/10.1016/j.cap.2013.08.019
  22. J. H. Yoon, H. J. Jung, J. T. Hong, J. Y. Park, S. Lee, S. W. Lee, and Y. H. Ahn, "Electronic band alignment at complex oxide interfaces measured by scanning photocurrent microscopy," Sci. Rep. 7, 3824 (2017). https://doi.org/10.1038/s41598-017-04265-9
  23. J. Park, Y. H. Ahn, and C. Ruiz-Vargas, "Imaging of photocurrent generation and collection in single-layer graphene," Nano Lett. 9, 1742-1746 (2009). https://doi.org/10.1021/nl8029493
  24. B. H. Son, J. K. Park, J. T. Hong, J. Y. Park, S. Lee, and Y. H. Ahn, "Imaging ultrafast carrier transport in nanoscale field-effect transistors," ACS Nano 8, 11361-11368 (2014). https://doi.org/10.1021/nn5042619
  25. Y. C. Kim, V. T. Nguyen, S. Lee, J. Y. Park, and Y. H. Ahn, "Evaluation of transport parameters in $MoS_2$/graphene junction devices fabricated by chemical vapor deposition," ACS Appl. Mater. Interfaces 10, 5771-5778 (2018). https://doi.org/10.1021/acsami.7b16177
  26. Y. H. Ahn, A. W. Tsen, B. Kim, Y. W. Park, and J. Park, "Photocurrent imaging of p-n junctions in ambipolar carbon nanotube transistors," Nano Lett. 7, 3320-3323 (2007). https://doi.org/10.1021/nl071536m
  27. Y. Li, W. Yan, Y. Li, S. Wang, W. Wang, Z. Bian, L. Xiao, and Q. Gong, "Direct observation of long electron-hole diffusion distance in $CH_3NH_3PbI_3$ perovskite thin film," Sci. Rep. 5, 14485 (2015). https://doi.org/10.1038/srep14485