Lee Hyeonseok, Huang Yu-Ting, Horn Mark W, Feng Shien-Ping
Department of Mechanical Engineering, the University of Hong Kong, Pok Fu Lam, Hong Kong.
Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, USA.
Sci Rep. 2018 Apr 3;8(1):5590. doi: 10.1038/s41598-018-23907-0.
Inverted perovskite solar cells incorporating RF sputtered NiO thin films as a hole transport layer and window layer are demonstrated. The electrical and optical properties of the NiO thin films are engineered using varied sputtering conditions. The localized states within bandgap owing to its crystal disorder and nonstoichiometric features affect the transmittance and the optical bandgap of the NiO thin films which in turn influences the J of the perovskite solar cells. In addition, the electrical properties of the NiO thin films can be also varied during sputtering condition affecting the concentration of nickel vacancies and the resulting hole concentration. The conductivity largely originates from the hole concentration relating to the density of states in the NiO thin films which influence the fill factor (FF) of the solar cells. The solar cells fabricated with the NiO thin films made at 4 Pa of deposition pressure show highest performance owing to excellent transmittance and wider bandgap along with moderate conductivity. With further optimization, the perovskite solar cells exhibit ~20 mA/cm of J and a 12.4% PCE (11.3% of averaged PCE).
展示了采用射频溅射氧化镍（NiO）薄膜作为空穴传输层和窗口层的倒置钙钛矿太阳能电池。通过改变溅射条件来调控NiO薄膜的电学和光学性质。由于其晶体无序和非化学计量特性，带隙内的局域态会影响NiO薄膜的透过率和光学带隙，进而影响钙钛矿太阳能电池的电流密度（J）。此外，在溅射过程中，NiO薄膜的电学性质也会发生变化，这会影响镍空位的浓度以及由此产生的空穴浓度。电导率主要源于与NiO薄膜态密度相关的空穴浓度，而这又会影响太阳能电池的填充因子（FF）。在4 Pa沉积压力下制备的NiO薄膜所制成的太阳能电池，因其具有优异的透过率、较宽的带隙以及适中的电导率，表现出最高的性能。经过进一步优化，钙钛矿太阳能电池呈现出约20 mA/cm的电流密度（J）和12.4%的光电转换效率（PCE）（平均PCE为11.3%）。
