Joshi Upendra A, Maggard Paul A
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
J Phys Chem Lett. 2012 Jun 7;3(11):1577-81. doi: 10.1021/jz300477r. Epub 2012 May 29.
A new p-type CuNb3O8 polycrystalline photoelectrode was investigated and was determined to have indirect and direct bandgap sizes of 1.26 and 1.47 eV, respectively. The p-type polycrystalline film could be prepared on fluorine-doped tin oxide glass and yielded a cathodic photocurrent under visible-light irradiation (λ > 420 nm) with incident photon-to-current efficiencies of up to ∼6-7% and concomitant hydrogen evolution. A Mott-Schottky analysis yielded a flat band potential of +0.35 V versus RHE (pH = 6.3) and a calculated p-type dopant concentration of ∼7.2 × 10(15) cm(-3). The conduction band energies are found to be negative enough for the reduction of water under visible light irradiation. A hole mobility of ∼145 cm(2)/V·s was obtained from J(I)-V(2) measurements using the Mott-Gurney relation, which is ∼50% higher than that typically found for p-type Cu2O. DFT-based electronic structure calculations were used to probe the atomic and structural origins of the band gap transitions and carrier mobility. Thus, a new p-type semiconductor is discovered for potential applications in solar energy conversion.
研究了一种新型的p型CuNb3O8多晶光电极，其间接带隙和直接带隙大小分别为1.26 eV和1.47 eV。这种p型多晶薄膜可以在氟掺杂氧化锡玻璃上制备，在可见光照射（λ>420 nm）下产生阴极光电流，入射光子到电流的效率高达约6-7%，并伴随析氢反应。莫特-肖特基分析得出相对于可逆氢电极（RHE，pH = 6.3）的平带电位为+0.35 V，计算出的p型掺杂剂浓度约为7.2×10(15) cm(-3)。发现导带能量足够负，能够在可见光照射下还原水。使用莫特-格尼关系通过J(I)-V(2)测量获得了约145 cm(2)/V·s的空穴迁移率，这比p型Cu2O通常的迁移率高约50%。基于密度泛函理论（DFT）的电子结构计算用于探究带隙跃迁和载流子迁移率的原子和结构起源。因此，发现了一种新型p型半导体，可用于太阳能转换的潜在应用。
