Development of simple hole-transporting materials for perovskite solar cells

Abstract

Three low-cost propeller-shaped small molecules based on a triphenylamine core and the high-performance donor molecule 7,7′-[4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl]bis[6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole] (DTS(FBTTh2)2) were investigated as hole-transporting materials in perovskite solar cells. Each hole-transporting material was designed with highly modular side arms, allowing for different bandgaps and thin-film properties while maintaining a consistent binding energy of the highest occupied molecular orbitals to facilitate hole extraction from the perovskite active layer. Perovskite solar cell devices were fabricated with each of the three triphenylamine-based hole-transporting materials and DTS(FBTTh2)2 and were compared to devices with 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) hole-transporting layers. Each of our triphenylamine hole-transporting materials and DTS(FBTTh2)2 displayed surface morphologies that were considerably rougher than that of spiro-OMeTAD; a factor that may contribute to lower device performance. It was found that using inert, insulating polymers as additives with DTS(FBTTh2)2 reduced the surface roughness, resulting in devices with higher photocurrents.

Near-Infrared-II Photodetectors Based on Silver Selenide Quantum Dots on Mesoporous TiO2 Scaffolds

“…Such a device structure was demonstrated by Guo et al using CuInSe 2 CQDs; however, the performance in the NIR region was poor. Spiro-OMeTAD (doped with tert -butylpyridine and Li-TFSI, as is common in the literature) was chosen as a hole-transporting layer (HTL) in our study because its HOMO energy level (−5.0 eV) is a good match for the valence band of Ag 2 Se QDs (−4.86 eV), , as illustrated in Figure d.…”

The Optimization of Direct Heteroarylation and Sonogashira Cross-Coupling Reactions as Efficient and Sustainable Synthetic Methods To Access π-Conjugated Materials with Near-Infrared Absorption

“…This heterogeneous alternative proved to be equally or more active than the common homogeneous catalysts Pd­(PPh 3 ) 4 , Pd­(PPh 3 ) 2 Cl 2 and Pd­(OAc) 2 offering advantages in terms of activity, selectivity, stability and trace metal contamination. Integrating the use of this heterogeneous catalyst whenever possible, we have established a large variety of materials that can be synthesized using this catalyst system. − …”