Thienylvinylenethienyl and Naphthalene Core Substituted with Triphenylamines—Highly Efficient Hole Transporting Materials and Their Comparative Study for Inverted Perovskite Solar Cells

In this report, two simple cost efficient solution processable small molecular hole transporting materials (HTMs) are synthesized and used successfully in inverted perovskite devices. These HTMs, namely (E)-4,4'-(ethene-1,2-diylbis(thiophene-5,2-diyl))bis(N,N-bis(4-methoxyphenyl)aniline) (TPA-TVT-TPA) and 4,4'-(naphthalene-2,6-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (TPA-NAP-TPA), are designed by using triphenylamine methoxy as common end capping groups with thienylvinylenethienyl and naphthalene cores respectively. They possess good solubility in common organic solvents. Additionally, they have not only appropriate highest occupied molecular orbital energy levels for good hole injection ability but also sufficient lowest unoccupied molecular orbital for electron blocking capability. The power conversion efficiency (PCE) of these HTMs based devices is found to be of 16.32% for TPA-TVT-TPA and 14.63% for TPA-NAP-TPA. Particularly, TPA-TVT-TPA exhibits an impressive V_oc of 1.07 V. The obtained performance is one of the highest performances in inverted perovskite layouts. The cut-price and straightforward synthesis with elegant scale up makes these classes of materials important for the industry to produce high-throughput printed perovskite solar cells for large area applications.