基于纳米多孔钛酸锂结构的染料敏化太阳电池复合光阳极研究

doi:10.15541/jim20150094

摘要/Abstract

摘要：

本研究探索了具有良好导电性能的多孔钛酸锂结构对传统氧化钛纳米晶光阳极的增强效果。以钛酸四丁酯、氢氧化锂为源, 采用溶胶-凝胶结合溶剂热反应和高温烧结方法, 制备了具有多孔结构的尖晶石型Li₄Ti₅O₁₂纳米粉体; 在表征其结晶性、微观形貌及孔结构的基础上, 将其与TiO₂纳米晶浆料复合, 制备复合光阳极, 并详细考察了钛酸锂掺量、结晶性和孔结构等对电池光电转换性能的影响规律。结果表明: 随热处理温度升高, Li₄Ti₅O₁₂结晶性增强, 晶粒尺寸明显增大, 比表面积下降。掺入Li₄Ti₅O₁₂粉体可以有效提高光阳极膜的染料负载量, 降低TiO₂/染料分子/电解液界面的电子传输阻抗, 从而明显提高复合光阳极的光电流密度(J_sc=13.91 mA/cm²)和开路电压(V_oc=0.8 V)。Li₄Ti₅O₁₂含量为1wt%的复合光阳极电池光电转化效率最好, 达到7.011%, 比纯TiO₂电池(效率: 5.384%)提高30%。

关键词: 染料敏化太阳电池, 复合光阳极, 钛酸锂, 光电转换

Abstract:

Li₄Ti₅O₁₂ with nanoporous feature and good conductivity was used to enhance the photoelectrochemical performance of traditional nanocrystalline TiO₂ photoanodes in Dye-sensitized Solar Cells (DSSC). Using tetrabutyl titanate and lithium hydroxide as raw materials, the spinel Li₄Ti₅O₁₂was obtained from common Sol-Gel, solvethermal and annealing processes. The dependence of the crystallinity, morphology and pore structure of the Li₄Ti₅O₁₂ powders on the annealing temperature were investigated. Li₄Ti₅O₁₂-TiO₂ hybrid photoanodes were prepared by the doctor-blade method using the slurry of TiO₂nanocrystallite which was blended with Li₄Ti₅O₁₂powders. The effects of the mass ratio of Li₄Ti₅O₁₂ to TiO₂, the crystallinity and the porous structure of Li₄Ti₅O₁₂ powders on the performance of DSSC were examined. Results show that with the annealing temperature increasing, the crystallinity of the Li₄Ti₅O₁₂ powders is enhanced, the crystallite size increased obviously, and the specific surface area decreased dramatically. The Li₄Ti₅O₁₂-TiO₂hybrid photoanodes exhibit higher dye-loading capacity and lower resistance at TiO₂/dye/electrolyte interface than does the pure TiO₂ counterpart, accompanied by higher J_sc (J_sc=13.91 mA/cm²) and V_oc(V_oc=0.8 V) values than by the TiO₂ photoanode. The highest conversion efficiency (7.011%) is achieved by 1wt% Li₄Ti₅O₁₂ hybrid cell, which is 30% higher than by the TiO₂nanocrystallite counterpart (5.384%).

Key words: dye-sensitized solar cells, hybrid photoanodes, lithium titanate, photoelectric conversion

中图分类号:

TM914

虎学梅, 顾正莹, 李效民, 高相东, 施鹰. 基于纳米多孔钛酸锂结构的染料敏化太阳电池复合光阳极研究[J]. 无机材料学报, 2015, 30(10): 1037-1042.

HU Xue-Mei, GU Zheng-Ying, LI Xiao-Min, GAO Xiang-Dong, SHI Ying. Hybrid Photoanodes Based on Nanoporous Lithium Titanate Nanostructures in Dye-sensitized Solar Cells[J]. Journal of Inorganic Materials, 2015, 30(10): 1037-1042.

图/表 9

图1 经过不同温度热处理LTO粉体的XRD图谱

Fig. 1 XRD patterns of LTO samples after heat-treatment at different temperatures (a) 500℃; (b) 600℃; (c) 700℃

图2 经过不同温度热处理LTO粉体的SEM照片

Fig. 2 SEM images of LTO powders after heat-treatment at different temperatures (a, b) 500℃; (c, d) 600℃; (e, f) 700℃

图3 不同温度热处理后LTO粉体的孔径分布曲线

Fig. 3 Pore size distribution curves for LTO powders after heat-treatment at different temperatures

图4 TiO2薄膜表面(a)和LTO-TiO2复合光阳极薄膜表面(b)及断面(c)的SEM照片

Fig. 4 Surface morphology of TiO2 photoanodes (a) and surface (b) and cross-section (c) morphologies of LTO-TiO2 hybrid photoanodes

图5 (a)不同温度热处理的5wt%LTO-TiO2复合光阳极透过光谱和(b)700℃热处理的不同LTO质量分数的复合光阳极透过谱

Fig. 5 (a) Transmission spectra of 5wt%LTO-TiO2 hybrid photoanodes after heat-treatment at different temperatures and (b) hybrid photoanodes with different LTO-TiO2 ratios after heat-treatment at 700℃

图6 不同组成的LTO-TiO2复合光阳极吸收光谱

Fig. 6 Absorption spectra of photoanodes with different LTO- TiO2 hybrid photoanodes

图7 染料敏化电池的电流密度-电压特性曲线

Fig. 7 J-V curves of DSSC devices based on LTO-TiO2 hybrid photoanodes

表1 LTO-TiO2复合电池光电转化参数

Table1 Photovoltaic properties of LTO-TiO2 DSSC

Ratio	V_oc/V	J_sc/(mA•cm^-2)	FF	η/%	R_ct/?	τ/ms
TiO₂	0.659	11.854	0.688	5.384	92.72	4.24
0.5wt%LTO-TiO₂	0.759	11.323	0.645	5.547	42.36	4.24
1wt%LTO-TiO₂	0.797	13.909	0.635	7.011	43.48	5.06
2wt%LTO-TiO₂	0.764	12.873	0.633	6.246	41.44	5.06
5wt%LTO-TiO₂	0.718	10.223	0.657	4.818	89.71	7.51

图8 不同纳米结构染料敏化太阳电池的电化学阻抗谱

Fig. 8 Electrochemical impedance spectra of different LTO-TiO2 DSSC (a) Nyquist plots; (b) Bode plots

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