Optimization of Dye-sensitized Solar Cells Prepared by Pechini Sol-Gel Method

doi:10.15541/jim20150576

Abstract

Abstract:

Functional TiO₂ films were prepared by using a facile one-step Pechini Sol-Gel method. The intrinsical contribution mechanism of film thickness to the photo-to-electric performance of DSSC was explored with analysis of interfacial charge recombination effects, on which, the characteristics of DSSC were optimized via film thickness controlling. The influence of TiO₂ film thickness on dye absorption, charge recombination process and photovoltaic performance of DSSC were by UV-Vis, electrochemical impedance spectroscopy and I-V test under dark condition, respectively. The results show that as TiO₂ film thickness increases, the light harvesting efficiency and photocurrent of DSSC increase, which were induced by the enhancement of dye absorption. However, the photovoltage decreases gradually with the increaese of electron recombination probability. As an increase, combination of the positive and negative effects above enables the Pechini-type DSSC efficiency first increase and then decline, with an optimum efficiency of 7.75% at the film thickness of 10.7 μm, in contrast to 6.5% of the routine method.

Key words: dye-sensitized solar cells, pechini Sol-Gel method, TiO2 film thickness, interfacial charge recombination

CLC Number:

TM914

YIN Yue-Feng, LIANG Gui-Jie, ZHANG Qiang, PAN Zheng, LI Wang-Nan, LI Zai-Fang. Optimization of Dye-sensitized Solar Cells Prepared by Pechini Sol-Gel Method[J]. Journal of Inorganic Materials, 2016, 31(7): 739-744.

Figures/Tables 7

Fig. 1 Different magnification SEM images of routine TiO2 films (a,b,c) and Pechini films (d, e, f)

Fig. 2 XRD patterns of TiO2 films of (a) routine-type and (b) Pechini-type

Fig. 3 Absorbance spectra of N719 dyes in ethanol (a) and the fitting plot of the extinction coefficient at 530 nm (b), and absor bance apectra of N7.9 dys in desorption solvent (c)

Table 1 Absorbance, EIS and photo-to-electric parameters of DSSC prepared by Pechini Sol-Gel method

	Method type	Thickness /μm	Q /(×10^-7, mol·cm^-2)	R_ct2 /Ω	R_ct3 /Ω	f_min /Hz	τ_e /ms	V_oc /V	J_sc /(mA·cm^-2)	ff	η /%
S1	Routine	3.3±0.1	0.583	36.7	8.7	15.5	10.3	0.701	5.43	0.675	2.57
S1	Pechini	3.2±0.1	0.715	44.5	10.6	11.2	14.2	0.756	6.27	0.683	3.24
S2	Routine	4.5±0.2	0.978	22.9	8.3	23.0	6.9	0.693	8.92	0.679	4.20
S2	Pechini	4.4±0.2	1.318	35.3	7.9	14.5	11.0	0.720	9.31	0.722	4.84
S3	Routine	7.5±0.2	1.524	13.7	7.7	46.4	3.4	0.690	11.73	0.721	5.85
S3	Pechini	7.3±0.1	2.095	23.4	9.3	26.3	6.1	0.702	13.18	0.726	6.72
S4	Routine	10.9±0.2	2.230	10.1	10.8	83.3	1.9	0.658	13.39	0.744	6.56
S4	Pechini	10.7±0.4	3.768	16.7	7.6	35.0	4.5	0.685	15.22	0.743	7.75
S5	Routine	12.9±0.3	3.441	6.6	7.2	100.2	1.3	0.662	13.87	0.719	6.60
S5	Pechini	12.6±0.3	5.304	13.1	8.3	87.3	1.8	0.632	12.68	0.717	5.74

Fig. 4 I-V curves of Pechini-type DSSC(a) Under illumination of 100 mW/cm2; (b) Under dark condition. Plots of (c) photovoltage/photocurrent-film thickness and (d) conversion efficiency-film thickness

Fig. 5 EIS spectra of Pechini-type DSSC with -0.7 V external bias potential under dark condition (a) Nyquist EIS; (b) Bode EIS. The top view in figure (a) is equivalent circuit of DSSC

Fig. 6 IPCE curves of Pechini-type DSSC

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