تخمین طول عمر و طول پخش الکترون در لایه‌های نیم رسانای نانومتخلخل به روش شبیه‌سازی گشت تصادفی در دو مقیاس

نوع مقاله: مقاله پژوهشی کامل

نویسندگان

دانشگاه بیرجند

چکیده

در این پژوهش با استفاده از یک مدل دو-مقیاسی، فرآیند پخش الکترون توأم با بدام افتادن در یک لایة نیم‌رسانای نانومتخلخل و با در نظرگرفتن مراکز بازترکیب شبیه‌سازی می‌شود. در مقیاس اول نقش توزیع حالت‌های جای‌گزیده از طریق تخمین زمان ماندگاری الکترون در هر نانوذره، با توجه به تعداد و آرایش همسایه‌های اول آن، محاسبه شده و در مقیاس دوم الکترون روی یک خوشة تراوش کننده بی‌نظم از نانوذرات پخش می‌شود. زمان ماندگاری الکترون در هر نانوذره به تعداد همسایگان اول آن بستگی دارد که در مقیاس اول محاسبه شده است. برخی از نانوذرات این خوشه با احتمال از پیش تعریف شده‌ای دارای مراکز بازترکیب هستند. نتایج شبیه‌سازی‌های ما نشان می‌دهند که مدل دو-مقیاسی در عین حال که سرعت محاسبات را به‌شدت افزایش می‌دهد، تخمین درستی از روند تغییر ضریب پخش برحسب تخلخل، که در تطابق با مشاهدات تجربی است ارائه می‌دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Estimation of electron diffusion length and life-time in nano-porous semi-conductors with a two-scale random walk method

نویسندگان [English]

  • Fatemeh Ebrahimi
  • Mahla Moghaddas
  • Hakimeh Koochi
University of Birjand
چکیده [English]

In this study, we modified the two-scale method proposed by Ebrahimi and Koochi to simulate electron diffusion in a disordered nano-structured semiconductor and study the effect of recombination process in localized traps, on electron transport. In the first scale, we estimate the mean electron residence time for nano particles with an arbitrary coordination number. In the second scale, we estimate the electron lifetime when it travels through a disordered percolating cluster of nano particles. The electron residence time on each particle was evaluated in the first scale. Some of the nano particles have recombination centers. We find that while employing the two-scale method decreases the computational time drastically, it produces the correct dependence of diffusion coefficients on the material’s porosity.

کلیدواژه‌ها [English]

  • Two-scale model
  • Porous semiconductor film
  • Random walk
  • Residence time of electron
  • Lifetime of electron
  • Diffusion length of electron

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[2] J. Bisquert, Physical electrochemistry of nanostructured devices, Physical Chemistry Chemical Physics 10 (2008) 49–72.

[3] J. Nelson, Continuous-time random-walk model of electron transport in nanocrystalline TiO2 electrodes, Physical Review B 59 23 (1999) 15374-15380.

 [4] J.A. Anta, J. Nelson, N. Quirke, Charge transport model for disordered materials: Application to sensitized TiO2, Physical Review B 65 (2002) 125324-125334.

[5] J.A. Anta, I. Mora-Ser, T. Dittrich, J. Bisquert, Interpretation of diffusion coefficients in nanostructured materials from random walk numerical simulation, Physical Chemistry Chemical Physics 10 (2008) 4478–4485.

[6] J.A. Anta, V. Morales-Florez, Combined effect of energetic and spatial disorder on the trap-limited electron diffusion coefficient of metal-oxide nanostructures, Physical Chemistry C 112 (2008) 10287–10293.

[7] M. Ansari-Rad, Y. Abdi, E. Arzi, Monte carlo random walk simulation of electron transport in dye-sensitized nanocrystalline solar cells: influence of morphology and trap distribution, Physical Chemistry C 116(2012) 3212−3218.

[8] J.P. Gonzalez-Vazquez, J.A. Anta, J. Bisquert, Determination of the electron diffusion length in dye-sensitized solar cells by random walk simulation: compensation effects and voltage dependence, Physical Chemistry C 114 (2010) 8552–8558.

[9] F. Ebrahimi, H. Koochi, A two-scale method for fast estimation of the charge-carrier diffusion coefficient in nano-porous semi-conductors, Physics: Condensed Matter 29(2017) 025901-025906.

 

 [10] H. Koochi, F. Ebrahimi, Geometrical effects on the electron residence time in semiconductor nano-particles, Chemical Physics 141 (2014) 094702-094708.

[11] K.D. Benkstein, N. Kopidakis, J. van de Lagmaat, A.J. Frank, Influence of the percolation network geometry on electron transport in dye- sensitized titanium dioxide solar cells, Physical Chemistry B 107 (2003) 7759-7767.

[12] J.P. Gonzalez-Vazquez, random walk numerical simulation of electron dynamics in solar cells based on disordered materials, Ph.D. Thesis, Sevilla, De Julio Del, (2012).

[13] D. Stauffer, A. Aharony, Introduction to Percolation Theory, Taylor & Francis: London, Washington DC, (1992).

[14] A. Ofir, S. Dor, L. Grinis, A. Zaban, T. Dittrich, J. Bisquert, Porosity dependence of electron percolation in nanoporous TiO2 layers, Chemical Physics 128 (2008) 1-9.

[15] N.W. Ashcroft, N.D. Mermin, Solid state physics, Saunders College, New York, (1976).

 [1] M. Gratzel, Review dye-sensitized solar cells, Photochemistry and Photobiology C: Photochemistry Reviews 4 (2003) 145–153.

[2] J. Bisquert, Physical electrochemistry of nanostructured devices, Physical Chemistry Chemical Physics 10 (2008) 49–72.

[3] J. Nelson, Continuous-time random-walk model of electron transport in nanocrystalline TiO2 electrodes, Physical Review B 59 23 (1999) 15374-15380.

 [4] J.A. Anta, J. Nelson, N. Quirke, Charge transport model for disordered materials: Application to sensitized TiO2, Physical Review B 65 (2002) 125324-125334.

[5] J.A. Anta, I. Mora-Ser, T. Dittrich, J. Bisquert, Interpretation of diffusion coefficients in nanostructured materials from random walk numerical simulation, Physical Chemistry Chemical Physics 10 (2008) 4478–4485.

[6] J.A. Anta, V. Morales-Florez, Combined effect of energetic and spatial disorder on the trap-limited electron diffusion coefficient of metal-oxide nanostructures, Physical Chemistry C 112 (2008) 10287–10293.

[7] M. Ansari-Rad, Y. Abdi, E. Arzi, Monte carlo random walk simulation of electron transport in dye-sensitized nanocrystalline solar cells: influence of morphology and trap distribution, Physical Chemistry C 116(2012) 3212−3218.

[8] J.P. Gonzalez-Vazquez, J.A. Anta, J. Bisquert, Determination of the electron diffusion length in dye-sensitized solar cells by random walk simulation: compensation effects and voltage dependence, Physical Chemistry C 114 (2010) 8552–8558.

[9] F. Ebrahimi, H. Koochi, A two-scale method for fast estimation of the charge-carrier diffusion coefficient in nano-porous semi-conductors, Physics: Condensed Matter 29(2017) 025901-025906.

 

 [10] H. Koochi, F. Ebrahimi, Geometrical effects on the electron residence time in semiconductor nano-particles, Chemical Physics 141 (2014) 094702-094708.

[11] K.D. Benkstein, N. Kopidakis, J. van de Lagmaat, A.J. Frank, Influence of the percolation network geometry on electron transport in dye- sensitized titanium dioxide solar cells, Physical Chemistry B 107 (2003) 7759-7767.

[12] J.P. Gonzalez-Vazquez, random walk numerical simulation of electron dynamics in solar cells based on disordered materials, Ph.D. Thesis, Sevilla, De Julio Del, (2012).

[13] D. Stauffer, A. Aharony, Introduction to Percolation Theory, Taylor & Francis: London, Washington DC, (1992).

[14] A. Ofir, S. Dor, L. Grinis, A. Zaban, T. Dittrich, J. Bisquert, Porosity dependence of electron percolation in nanoporous TiO2 layers, Chemical Physics 128 (2008) 1-9.

[15] N.W. Ashcroft, N.D. Mermin, Solid state physics, Saunders College, New York, (1976).