电化学沉积非晶NiO_xH_y膜的电致变色特性及其机理

Electrochromic Performance and Mechanism of Noncrystalline NiO_x H_y Thin Films Fabricated by Electrochemical Deposition

研究了用电化学方法在 Sn O2 基底上沉积的 Ni Ox Hy 膜电致变色特性 ,该膜是一种富氧结构 ,具有优良的变色特性 ,其透射式光密度ΔOD在可见光区可达 1以上 .Ni Ox Hy 膜在 KOH电解液中的电致变色行为是由质子的注入或萃取所决定 .H+注入并占据 Ni空位 ,会使一部分 Ni3+转化为 Ni2 + ,Ni3+的减少将导致光透性增强 ,这是因为Ni的 d电子能级在 Ni O6 八面体晶场中被分裂为 t2 g和 eg 能级 .H+的注入使 Ni3+的 t2 g能级被电子填满 ,变为 Ni2 + ,导致光学透明 .反之 ,H+ 的萃取使 t2 g能级出现空穴 ,即形成 Ni3+ 。

The electrochromic(EC) properties of the electrochemically deposited NiO x H y thin films on glass substrates coated with SnO 2 thin films were studied. The coloring and bleaching transmission rate C t(which is the ratio of coloring light transmission density I c to bleaching light transmission density I b) is found to be 1/10 in the visible spectrum. In KOH electrolyte, the EC process is just the insertion and extraction of a proton or H +. OH - only provides an oxidation and redoxation environment related to coloring/bleaching process. The insertion of H + and its sequential filling the Ni vacancy will cause Ni 3+ to turn into Ni 2+ . The reduction of Ni 3+ then leads to the increase of light absorbance.It is because that the d energy level splits into t 2g and e g energy levels in the octahedral crystal field of NiO 6. The insertion of H + makes t 2g energy level of Ni 3+ occupied by electronics and then transparent.On the contrary, the extraction of H + causes t 2g energy level to lose some electronics and form Ni 3+ , resulting in the increase of light absorbance.