Investigation of Hole-Transporting Poly(triarylamine) on Aggregation and Charge Transport for Hysteresisless Scalable Planar Perovskite Solar Cells

Abstract

Organometallic halide perovskite solar cells (PSCs) have unique photovoltaic properties for use in next-generation solar energy harvesting systems. The highest efficiency of PSCs reached 22.1% on a laboratory scale of <0.1 cm device area. Thus, scaling up is the next step toward commercialization, but the difficulty in controlling the quality of large-area perovskite thin films remains a fundamental challenge. It has also been frequently reported that the J- V hysteresis is intensified in PSCs with areas larger than 1 cm. In this study, we have fabricated a large-area perovskite layer using PbICl films, providing an intrinsic porous layer and enhancing the uniformity of the perovskite layer at areas larger than 1 cm. Furthermore, we have investigated the polymeric properties of the prevalent hole-transporting material poly(triarylamine) (PTAA) with its photovoltaic performance. Two types of PTAAs, poly[bis(4-phenyl)(2,4-dimethylphenyl)amine] and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], were compared. A series of PTAAs with different molecular weights ( M) and polydispersity indices were studied, as the molecular weight of the PTAA is a key factor in determining the electrical properties and photovoltaic performance of the system. The fabricated PSCs with an aperture area of 1 cm based on a high-molecular-weight PTAA achieved a power conversion efficiency of 16.47% with negligible hysteresis and excellent reproducibility.

The Molecular Weight Dependence of Thermoelectric Properties of Poly (3-Hexylthiophene)

“…Aggregates like those found in the samples are commonly observed by adding LiTFSI solved in acetonitrile [34]. The aggregation and morphology changes are typically associated with noncovalent interactions such as hydrogen bonds, electrostatic interactions, aromatic interactions, and hydrophilic/hydrophobic effects [45]. The large grainy aggregates might be attributed to the formation of solid LiTFSI within the P3HT layer, because acetonitrile has a lower boiling point compared to the other solvents [34,35,46].…”

The Impact of Hybrid Compositional Film/Structure on Organic–Inorganic Perovskite Solar Cells

“…Meanwhile, the creation of mesoporous oxide films, such as TiO 2 [ 94 , 95 , 96 ], Al 2 O 3 [ 10 , 97 , 98 ], and ZrO 2 [ 99 , 100 ], have also been extensively investigated. A p-type hole-transporting material, such as polytriarylamine (PTAA) [ 101 , 102 , 103 , 104 ] or 2,2′,7,7′-tetrakis-( N , N -di- p- methoxyphenylamine)9,9′-spirobifluorene (spiro-OMeTAD) [ 105 , 106 ], is commonly used as the HTL in PSCs. The ETL/HTL must have a CB (conduction band)/VB (valence band) that is compatible with that of the perovskite that is used in planar/mesoporous perovskite solar cells.…”

Limitations of a polymer-based hole transporting layer for application in planar inverted perovskite solar cells

“…12,13 Numerous attempts were made to improve the stability of devices employing PTAA, mainly via doping or application of interfacial barriers to prevent ion migration from the light harvester and extend operational lifetime. [14][15][16][17][18] Although satisfactory improvements were suggested by many groups, there is surprisingly a low number of studies concerning the stability of PTAA itself. Namely, literature reports on this topic are usually related to PTAA stability aer heat and moisture induced oxidation.…”