Double-shelled ZnO/CdSe/CdTe nanocable arrays for photovoltaic applications: microstructure evolution and interfacial energy alignment
Double-shelled ZnO/CdSe/CdTe nanocable arrays for photovoltaic applications: microstructure evolution and interfacial energy alignment
复制标题
用于光伏应用的双壳 ZnO/CdSe/CdTe 纳米电缆阵列：微观结构演化和界面能量对准
DOI：
10.1039/c2jm32253f
复制
发表时间：
2012-01-01
影响因子：
--
通讯作者：
Duan, Jinxia
中科院分区：
文献类型：
--
作者：
Wang, Hao;Wang, Tian;Duan, Jinxia
以氧化锌纳米棒阵列为核心，采用电沉积法制备了一系列高密度的双壳和单壳的ZnO/CdSe/CdTe、ZnO/CdTe、ZnO/CdTe和ZnO/CdSe纳米阵列作为光阳极。对于ZnO/CdSe/CdTe纳米阵列，均匀的CdSe和CdTe纳米壳层由闪锌矿相纳米晶组成，其平均尺寸范围分别为10-20 nm和7-15 nm，并在两者之间形成了致密而连续的界面。根据接触前块体材料的能带偏移和接触后的界面费米能级漂移，推导出了双层壳层纳米可控阵列的界面能级排列。纳米线缆的Cd Te/Cd Se界面的负带偏移量为-0.16 eV，而对于ZnO/Cd Se/Cd Se纳米线缆，Cd Te的带边位于Cd Se以上，其导带偏移量为0.16 eV。这种阶梯式的能带排列，加上紧密的界面，沿径向较少的晶界，以及沿轴向快速的传输速率，使得ZnO/CdSe/CdTe纳米阵列光阳极具有接近14.3 mA cm(-2)的饱和光电流。这是在45 mW cm(-2)的AM1.5G模拟太阳光照射下进行的，远高于ZnO/CdTe/CdSe、ZnO/CdSe或ZnO/CdTe纳米阵列。
A series of high-density double-and single-shelled ZnO/CdSe/CdTe, ZnO/CdTe/CdSe, ZnO/CdTe and ZnO/CdSe nanocable arrays were synthesized as photoanodes by an electrodeposition method using ZnO nanorod arrays as cores. For ZnO/CdSe/CdTe nanocable arrays, the uniform CdSe and CdTe nanoshells were composed of zinc-blende phase nanocrystals with a respective average size range of 10-20 nm and 7-15 nm, and formed a compact and continuous interface in between. Based on the band offset of the bulk material before contact and the interfacial Fermi level shift after contact, the energy level alignments at the CdSe/CdTe and CdTe/CdSe interface were deduced for the double-shelled nanocable arrays. The CdTe/CdSe interface of the ZnO/CdTe/CdSe nanocables has a negative band offset of -0.16 eV whilst for ZnO/CdSe/CdTe nanocables, the band edge of CdTe lies above CdSe with a conduction band offset of 0.16 eV at the CdSe/CdTe interface. Such a stepwise band alignment, together with the compact interface, fewer grain boundaries along the radial direction, and the fast transfer rate along the axial direction of the nanocables, makes the ZnO/CdSe/CdTe nanocable arrays photoanode have a saturated photocurrent of similar to 14.3 mA cm(-2). This is under the irradiation of AM1.5G simulated sunlight at 45 mW cm(-2), which is greatly higher than ZnO/CdTe/CdSe, ZnO/CdSe or ZnO/CdTe nanocable arrays.