电荷传输理论
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Operating principle of the dye solar cell
Structure and operation of the dye solar cell
a
3
•Principle of EIS
• Conditions
1.1. steady state operating conditions(light intensity,cell temperature, the operating point along its IV curve)
•1-103(ω2): the TiO2/dye/electrolyte interface(Z2) •0.1 -1 (ω3)Hz:the Nernstian diffusion in the electrolyte (Z3)
1.2. A small amplitude harmonic AC voltage modulation VAC (ω, t) is superimposed on the DC voltage of the cell
3. measured while scanning the modulation frequency f = ω/2π over a certain range
Equivalent Circuit Model
Reporter:Xiaoli Fang Date:2011.9.4
a
1
Content
• Principle of EIS • Eq来自百度文库ivalent circuit models
a
2
The main back-reactions limiting the photocurrent are : (a) radiationless relaxation of the excitedstate of the dye (b) recombination of the electrons with the oxidized dye (c) and with the tri-iodide in the electrolyte
Liyuan Han,Naoki Koide,etal.Appl.Phys.Lett.,86, 21a3501 (2005).
6
•The resistance element (Rs) in the high frequency region(>106Hz) is related to the sheet resistance of the TCO layer •103 -105Hz(ω1):the charge transport at the TiO2/conducting layeror Pt/electrolyte interfaces(Z1)
•The last low frequency:the Warburg diffusion of the ions in theelectrolyte.
Shi-Woo Rhee,Woosung Kwon.Korean J. Chem. Eng., 28(7), 1481-1494 (2011).
Huajun Tian, Linhua Hu,etal.J. Mater. Chem.,2011.a
•The intermediate frequency semicircle:the recombination reaction and the charge accumulation at theTiO2/electrolyte interface.Thus, the middle semicircle can be enlarged with the increase of Rr (retarding the recombination reaction). The bigger the diameter of the middle frequency semicircle in the Nyquist plots, the slighter is the electron recombination at the dyed TiO2/electrolyteinterface.
•R2：the resistance of the diode in a DSC •R3：Warburg impedance
Rs=Rh+R1+R3
•Rsh： a shunt resistance, estimated to be 2 kΩ/cm2
Liyuan Han,Naoki Koide,etal.Appl.Phys.Lett.,84(13),2433-2435(2004).
5
•Z1:impedances related to charge transport at the Pt counter electrode in the high frequency region(103–105Hz)
•Z2:TiO2 /dye/electrolyte interface in the middle-frequency region(1–103Hz) •Z3:Nernstian diffusion within the electrolyte in the low-frequency region(2×10-2-1Hz ) •Rh : a resistance in the high-frequency range over 106 Hz TCO
result
Janne Halme, Paula Vahermaa,etal. Adv. Mater., 22, E210–E234 (2010).
a
4
• At very high frequencies:current will flow through Rs and the capacitors in circuit elements (2),(3) and (4). •The high frequency semicircle :the parallel combination of Rc tand CCE at the electrolyte/counter electrode interface.
Structure and operation of the dye solar cell
a
3
•Principle of EIS
• Conditions
1.1. steady state operating conditions(light intensity,cell temperature, the operating point along its IV curve)
•1-103(ω2): the TiO2/dye/electrolyte interface(Z2) •0.1 -1 (ω3)Hz:the Nernstian diffusion in the electrolyte (Z3)
1.2. A small amplitude harmonic AC voltage modulation VAC (ω, t) is superimposed on the DC voltage of the cell
3. measured while scanning the modulation frequency f = ω/2π over a certain range
Equivalent Circuit Model
Reporter:Xiaoli Fang Date:2011.9.4
a
1
Content
• Principle of EIS • Eq来自百度文库ivalent circuit models
a
2
The main back-reactions limiting the photocurrent are : (a) radiationless relaxation of the excitedstate of the dye (b) recombination of the electrons with the oxidized dye (c) and with the tri-iodide in the electrolyte
Liyuan Han,Naoki Koide,etal.Appl.Phys.Lett.,86, 21a3501 (2005).
6
•The resistance element (Rs) in the high frequency region(>106Hz) is related to the sheet resistance of the TCO layer •103 -105Hz(ω1):the charge transport at the TiO2/conducting layeror Pt/electrolyte interfaces(Z1)
•The last low frequency:the Warburg diffusion of the ions in theelectrolyte.
Shi-Woo Rhee,Woosung Kwon.Korean J. Chem. Eng., 28(7), 1481-1494 (2011).
Huajun Tian, Linhua Hu,etal.J. Mater. Chem.,2011.a
•The intermediate frequency semicircle:the recombination reaction and the charge accumulation at theTiO2/electrolyte interface.Thus, the middle semicircle can be enlarged with the increase of Rr (retarding the recombination reaction). The bigger the diameter of the middle frequency semicircle in the Nyquist plots, the slighter is the electron recombination at the dyed TiO2/electrolyteinterface.
•R2：the resistance of the diode in a DSC •R3：Warburg impedance
Rs=Rh+R1+R3
•Rsh： a shunt resistance, estimated to be 2 kΩ/cm2
Liyuan Han,Naoki Koide,etal.Appl.Phys.Lett.,84(13),2433-2435(2004).
5
•Z1:impedances related to charge transport at the Pt counter electrode in the high frequency region(103–105Hz)
•Z2:TiO2 /dye/electrolyte interface in the middle-frequency region(1–103Hz) •Z3:Nernstian diffusion within the electrolyte in the low-frequency region(2×10-2-1Hz ) •Rh : a resistance in the high-frequency range over 106 Hz TCO
result
Janne Halme, Paula Vahermaa,etal. Adv. Mater., 22, E210–E234 (2010).
a
4
• At very high frequencies:current will flow through Rs and the capacitors in circuit elements (2),(3) and (4). •The high frequency semicircle :the parallel combination of Rc tand CCE at the electrolyte/counter electrode interface.