多孔BiFeO_3薄膜的光伏效应研究

Study on the Photovoltaic Effect in Porous BiFeO_3 Films

采用溶胶-凝胶法,在不同退火温度下在FTO/玻璃衬底上制备了多孔BiFeO3薄膜并对薄膜的光伏特性进行了研究。结果表明,在450-600℃退火的薄膜,均呈高度（100）择优取向;所有薄膜均为多孔薄膜,450℃、500℃、550℃和600℃退火的薄膜的孔径大小分别为2μm,2μm,6μm和1μm。孔隙的出现与加入乙醇胺的量直接相关,同时能够增强对光的吸收。450℃、500℃、550℃和600℃退火的薄膜的光学带隙分别为2.31 eV,2.50 eV,2.51 eV,和2.62 eV,所有光学带隙显著低于通常报道的结果。450℃与500℃退火的BiFeO3薄膜具有较强的光电导效应,而600℃退火的BiFeO3薄膜具有较强的体光伏效应。BiFeO3薄膜中的体光伏效应来自铁电极化产生的内建电场。

Porous BiFeO3 films were fabricated on FTO /glass substrates by sol-gel method. The photovoltaic properties of the porous BiFeO3 films were studied. The results show that the films are highly（ 100） preferentially oriented. All films are porous,the pore-radius of the films annealed at 450-600 ℃are 2 μm,2 μm,6 μm and 1 μm,respectively. The pores are related to the 2-Aminoethanol and they can promote the absorption. The porous films exhibit intense absorbance around 450 nm. The band gaps are2. 31 eV,2. 50 eV,2. 51 eV and 2. 62 eV for the films annealed at 450 ℃,500 ℃ 550 ℃ and 600 ℃,respectively. Significant ferroelectric photovoltaic effect was observed in the porous BiFeO3 film annealed at 600 ℃,the short circuit current density is 3. 67 × 10^- 8A /cm2 and open circuit voltage is- 0. 262 V.