School of Photovoltaic and Renewable Energy Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia.
ACS Appl Mater Interfaces. 2017 Oct 4;9(39):33841-33854. doi: 10.1021/acsami.7b09153. Epub 2017 Sep 25.
The current work reports the lithium (Li) doping of a low-temperature processed zinc oxide (ZnO) electron transport layer (ETL) for highly efficient, triple-cation-based MAFARbPbI (MA: methylammonium, FA: formamidinium, Rb: rubidium) perovskite solar cells (PSCs). Lithium intercalation in the host ZnO lattice structure is dominated by interstitial doping phenomena, which passivates the intrinsic defects in ZnO film. In addition, interstitial Li doping also downshifts the Fermi energy position of Li-doped ETL by 30 meV, which contributes to the reduction of the electron injection barrier from the photoactive perovskite layer. Compared to the pristine ZnO, the power conversion efficiency (PCE) of the PSCs incorporating lithium-doped ZnO (Li-doped) is raised from 14.07 to 16.14%. The superior performance is attributed to the reduced current leakage, enhanced charge extraction characteristics, and mitigated trap-assisted recombination phenomena in Li-doped devices, thoroughly investigated by means of electrochemical impedance spectroscopy (EIS) analysis. Li-doped PSCs also exhibit lower photocurrent hysteresis than ZnO devices, which is investigated with regard to the electrode polarization phenomena of the fabricated devices.
本工作报道了低温处理的氧化锌（ZnO）电子传输层（ETL）的锂（Li）掺杂，用于高效的基于三阳离子的 MAFARbPbI（MA：甲脒，FA：甲脒，Rb：铷）钙钛矿太阳能电池（PSC）。Li 在 ZnO 晶格结构中的嵌入主要由间隙掺杂现象主导，该现象钝化了 ZnO 薄膜中的本征缺陷。此外，间隙 Li 掺杂还使 Li 掺杂 ETL 的费米能级位置向下移动了 30 meV，这有助于降低从光活性钙钛矿层注入的电子的势垒。与原始 ZnO 相比，掺入 Li 掺杂 ZnO（Li 掺杂）的 PSCs 的功率转换效率（PCE）从 14.07%提高到 16.14%。优异的性能归因于 Li 掺杂器件中电流泄漏的减少、电荷提取特性的增强和陷阱辅助复合现象的缓解，通过电化学阻抗谱（EIS）分析进行了彻底研究。Li 掺杂 PSCs 也表现出比 ZnO 器件更低的光电流滞后，这与所制备器件的电极极化现象有关。
