The exploration of alternative low-cost molecular hole-transporting materials (HTMs) specifically for both high efficient and stable perovskite solar cells (PSCs) is a relatively new research area. Two novel HTMs using the thiophene core were designed and synthesized (Z25 and Z26). The Z26-based perovskite solar cells exhibited a remarkable overall power conversion efficiency (PCE) of 20.1 %, which is comparable to 20.6% obtained by spiro-OMeTAD-based device. Importantly, the devices based-on Z26 show better stability 2 compared to devices based on Z25 and spiro-OMeTAD when aged under ambient air of 30% or 85% relative humidity in the dark and under continuous full sun illumination at maximum power point tracking respectively. The presented results clearly qualify a simple strategy by introduction of double bonds to design hole transporting materials for highly efficient and

Two TPB-based HTMs were synthesized and their energy levels were tuned to match with perovskite by introducing electron-donating groups asymmetrically. The TPBC based doping-free perovskite solar cell afforded an impressive PCE of 13.10% under AM 1.5G illumination, which is the first case of an effective device with TPB-based doping-free HTMs.

Three hole-transporting materials (HTMs) based on the phenothiazine core containing 4,4-dimethyltriphenylamine (Z28), N-ethylcarbazole (Z29), and 4,4-dimethoxytriphenylamine (Z30) as the peripheral groups connected by double bonds were designed and synthesized. The HTMs were tested in mixed cation/anion perovskite solar cells (PSCs) of the composition [(FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 ]. A power conversion efficiency (PCE) of 19.17% under 100 Mw cm −2 standard AM 1.5G solar illumination was obtained using Z30. Importantly, the devices based on Z30 show better stability compared to those using Z28 and Z29 when aged under ambient air of 40% relative humidity in the dark for 1008 h and under continuous sunlight soaking without encapsulation for 600 h. These results indicate that the 4,4-dimethoxytriphenylamine is a promising peripheral group in combination with the phenothiazine core, providing an alternative to develop small molecular HTMs for efficient and stable PSCs.

The overall prevalence of parent-reported symptoms of sleep disorders in a large sample of children in Beijing, China, was comparable to that reported in other countries, although the prevalence of some specific symptoms differed somewhat.

Two star-shaped TPA-based small-molecule materials(Z1012 and Z1013)were designed and synthesized in this paper. These molecules show high hole mobility and suitable energy levels for CH3NH3PbI3-based perovskite solar cells. Photovoltaic cells based on the Z1013 without any dopants or additives achieve an excellent power conversion efficiency (PCE) of 15.4%, which is comparable to devices based on state-of-art p-doped spiro-OMeTAD. Moreover, the devices based on these two HTMs show much better stability than that of devices based on spiro-OMeTAD when aging in ambient air both at room temperature and 80 ℃.These results demonstrate that star-shape TPAs could be excellent dopant-free HTMs for perovskite solar cells and hold promise to replace the p-doped spiro-OMeTAD, which is important for the fabrication of cost-effective and stable devices.