P3HT with Zn(C_6F_5)_2 as p-Type Dopant for the Enhanced Performance of Planar Perovskite Solar Cells

摘要

The molecular organic Lewis acid bis(pentafluorophenyl)zinc [Zn(C_6F_5)_2] isreported as an efficient p-type dopant for poly(3-hexylthiophene-2,5-diyl) (P3HT),to be used as hole-transporting material (HTM) in perovskite solar cells (PSCs) forthe first time. To date, the most efficient PSCs use lithium bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) and 4-tert-butylpyridine (tBP) as standardadditives for HTMs. However, such dopants can induce deleterious effects ondevice stability. Herein, the effect of the concentration of Zn(C_6F_5)_2 in P3HT HTMon the performance of PSCs is investigated. The P3HT-based PSCs using a lowconcentration of the dopant (0.025 mol%) in the HTM layer exhibit the bestperformance and the highest power conversion efficiency (PCE) of 17.49%, whichis almost 3.5% higher than the achieved PCE for pristine P3HT-based PSCs. Theorigin of the improved performance for PSCs is further investigated, by studyingthe conductivity and hole mobility of the thin films based on pristine and dopedP3HT. Adding a small amount of Zn(C_6F_5)_2 to P3HT increases its thin-film holemobility and its hole extraction ability.