New Efficient 1,1′‐Bi‐2‐naphthylamine‐Based Hole‐Transporting Materials for Perovskite Solar Cells

Abstract

Two new efficient hole transporting materials (HTMs) Q216 and Q219 based on C2‐symmetric 1,1′‐bi‐2‐naphthylamine central core have been synthesized. The bis(4‐methoxyphenyl)amine‐substituted 9H‐carbazole were chose as end groups to link with the central core. The two HTMs have suitable molecular orbital energy levels, being well matched with that of CH3NH3PbI3 and carbon counter electrode. By introducing bis(4‐methoxyphenyl)amine unit (BMPA) to “3” position in carbazole donor, Q219 exhibits smaller dihedral angle between carbazole and naphthyl unit than Q216 with “2”‐BMPA, which may improve the electron donor ability of carbazole and favors to charge transport. The highest power conversion efficiency of PSC based‐Q219 is 9.31 %. EIS and IMVS measurements confirm that Q219 reduces charge recombination in perovskite solar cells (PSCs). Accordingly, the PSC with Q219 favors a 99 mV higher open circuit voltage than that of the Q216. The results provide some useful ideas to further design more promising structure of HTMs.

Boosting inverted perovskite solar cell performance by using 9,9-bis(4-diphenylaminophenyl)fluorene functionalized with triphenylamine as a dopant-free hole transporting material

“…Furthermore, there are few earlier studies reporting the effect of substitution at different positions of small molecular HTMs on PSCs' performance. 57,58 The synthesis strategy of TPA-2,7-FLTPA-TPA and TPA-3,6-FLTPA-TPA is illustrated in Scheme 1, and a detailed synthesis procedure can be found in the Experimental section. Briefly, 4,4 0 -(2,7-dibromo-9H-uorene-9,9-diyl)bis(N,N-diphenylaniline) (compound 2) was made from commercial 2,7-dibromo-9Hfluoren-9-one (compound 1) with excessive triphenylamine in methanesulfonic acid at 140 o C for 48 h. Meanwhile, in order to synthesize 4,4 0 -(3,6-dibromo-9H-uorene-9,9-diyl)bis(N,Ndiphenylaniline) (compound 5), 3,6-dibromo-9H- uoren-9-one (compound 4) was prepared by using commercially available 3,6-dibromophenanthrene-9,10-dione (compound 3) in the presence of potassium hydroxide (KOH) and potassium permanganate (KMnO4) at 130 o C for 72 h. Afterwards, compound 4 was used as the starting material to synthesize compound 5 under similar reaction conditions mentioned above.…”

Density Functional Theory Investigation of Carbon Dots as Hole‐transport Material in Perovskite Solar Cells

“…As reported previously, there is an indirect impact of structural geometry on the charge collection efficiency (h col ) and the rate of interfacial charge recombination ,. The existence of an alkyl chain in HTMs changes their physical and chemical properties and therefore influences the performance of PSCs ,.…”

“…While many improvements have been achieved by changing the PSC constituents, development of superior quality HTMs is relatively little. Spiro‐OMeTAD (2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxy‐phenylamine)‐9,9′‐spiro‐ bi‐fluorene) is one of the most widely used HTMs in recently developed PSCs ,,. Based on its special characteristics of having a stable amorphous structure, excellent ability to form thin films and good electrical conductivity upon doping led to its use as an HTM ,.…”

A Density Functional Theory Study of two-dimensional post-transition metal chalcogenides and halides for interfacial charge transport in Perovskite Solar Cells

“…A PSC device comprises layered architecture with fluorine doped tin-oxide (FTO) glass, compact titanium oxide (TiO2), perovskite, hole transport material (HTM) and then counter electrode layers [5][6][7] . According to the cell operation principle, the HTMs shall have a higher energy valence band maximum (VBM) position, and the ETMs should have a lower energy conduction band minimum (CBM) than that of the perovskite 8 . Despite reasonably well-performing materials that were tried and tested as ETMs and HTMs in PSCs, there is a need for cost-effective, simple structured materials for electron and hole transport.…”