Bipyridine衍生物對鹵化鉛鈣鈦礦表面修飾及光伏性能的影響

Abstract

本研究將2,2’-bipyridine (Bpy)、1,10-phenanthroline (Phen) 和2,9-dimethyl-1,10-phenanthroline (DMPhen) 作為鈍化劑加入鈣鈦礦太陽能電池中的鈣鈦礦層。鈍化劑可以藉由修復薄膜中的缺陷/孔洞與阻擋晶格裂解，建立鈣鈦礦晶粒之間的快速電荷轉移通路、抑制電荷復合、延長載流子壽命。鈍化劑使用三種方式加入鈣鈦礦太陽能電池中：(1) 鈍化劑與鈣鈦礦前驅物一同溶解於溶劑中；(2) 將含有鈍化劑的反溶劑滴入鈣鈦礦薄膜進行再結晶；(3) 旋塗一層鈍化劑薄膜覆蓋至鈣鈦礦薄膜上。根據光電轉換效率結果，發現旋塗一層鈍化劑薄膜能更有效的填充鈣鈦礦晶粒間的缺陷。與Bpy修飾的薄膜相比，由結構更剛性的Phen和DMPhen所鈍化的薄膜更能抑制PbI2和δ-FAPbI3的形成，並具有優良的導電性與更長的電子壽命。藉由鈍化劑的立體障礙提升能降低胺類化合物的聚集，從而減少介面電荷累積。與未修飾的薄膜相比(9.31%)，添加DMPhen (2.5 mg mL-1於對二氯苯) 可顯著提升其元件的光電轉換效率至14.65%，歸因於DMPhen與鉛的配位較強，且能更好地抑制鈣鈦礦去質子化。進一步將DMPhen的濃度從2.5 mg mL-1調整為1.5 mg mL-1後，元件之填充因子可以從0.57增加到0.73，使光電轉換效率從11.16%提高到14.86%，填充因子從0.57增加到0.73。

Three aromatic amines, i.e., 2,2’-bipyridine (Bpy), 1,10-phenanthroline (Phen), and 2,9-dimethyl-1,10-phenanthroline (DMPhen), were introduced as the surfactant of light-harvesting perovskite layer, Cs0.05(FA0.94MA0.06)0.95]1.17, in perovskite solar cell (PSCs). Aromatic amines are beneficial to charge-transfer among perovskite grains, suppressing charge recombination and extending carrier lifetime, due to reduced film defects/pin-holes and retarded crystal decomposition. Three strategies were adopted to increase the interactions between a surfactant and perovskite film: (1) mixing of the perovskite precursors with a surfactant in solution; (2) using anti-solvents containing a surfactant to improve the crystallinity of perovskite film; (3) layer-by-layer spin-coating a perovskite film covered by a surfactant film. Layer-by-layer spin-coating improved the contact among perovskite grains. Compare to the Bpy-passivated film, the surfactant having a more rigid phenanthroline segment (Phen and DMPhen) enhanced the film conductivity, reduced the formation of PbI2 and δ-FAPbI3, and extended the electron lifetime of the photoexcited state. More sterically congested hindrance surfactant had less molecular aggregations and thereby reduced the interfacial charge accumulation. Compared to a reference cell (9.31%), the addition of rigid DMPhen (2.5 mg mL-1 in chlorobenzene) greatly improved the cell performance (14.65%) owing to the stronger lead-DMPhen coordination and the better suppression of deprotonation the ammonium in perovskite. After adjusting the concentration of DMPhen from 2.5 mg mL-1 to 1.5 mg mL-1, the cell performance enhanced from 11.16% to 14.86% due to the FF increased from 0.57 to 0.73.