氮掺杂二氧化钛纳米棒阵列的制备和光电转化性能表征

Preparation and photoelectrical conversion performance of nitrogen doped titanium dioxide nanorod arrays

以氨水为氮源,在掺杂氟的SnO2导电玻璃(SnO2:F,FTO)基底上通过水热法生长出氮掺杂单晶金红石相TiO2纳米棒阵列。XPS检测证明,底物中只有很少量的氮元素能进入到TiO2中,并以O—Ti—N形态存在。随着氮掺杂浓度的升高,TiO2纳米棒长度增加,(002)晶面相对于未掺杂TiO2生长迅速。样品的吸收光谱未发生明显变化,说明半导体的禁带宽度(或能隙大小)没有受到氮掺杂的影响。在光电转化中,体系在模拟太阳光辐射下的光电流响应和外量子效率都有大幅改善,最高值分别达到0.15mA/cm2和3.1%,均为空白TiO2的3.8倍。然而,氮浓度的继续增加会导致TiO2纳米棒团聚,促使光致电荷在传输过程中发生复合现象;过量的氨水还会与底物直接发生水解反应,不利于基底上纳米棒的生长。所以,适量浓度的氮掺杂TiO2纳米棒阵列是一种具有发展前景的太阳能电池材料。

Nitrogen doped single-crystal rutile TiO2nanorod arrays have been prepared on transparent conductive fluorine-doped tin oxide（FTO）substrates through a facile hydrothermal process,using aqueous ammonia as nitrogen source.The characterization by XPS indicated that only a small amount of nitrogen in reactants was added into TiO2and formed O—Ti—N structure.The nanorod length and diffraction intensity of the（002）lattice plane increased sharply with the doping concentration.The absorption spectrum of N-doped samples did not change evidently in comparison to undoped samples,indicating that the doping in this study had little effect on bandgap energy.However,photocurrent response and external quantum efficiency improved obviously under the irradiation of a solar simulator,and the highest values reached 0.15mA/cm2 and 3.1%,respectively,both of which were about 3.8times of those of undoped TiO2.On the other hand,the introduction of too much nitrogen would induce the aggregation of TiO2nanorods,which leads to the recombination of photogenerated charges.Excessive ammonia reacted directly with the reactants through the hydrolysis,which thus inhibited the growth of the nanorods on FTO substrates.Therefore,the TiO2nanorod doped with moderate nitrogen has potential applications in solar cells.