Pyridine Bridging Diphenylamine-Carbazole with Linking Topology as Rational Hole Transporter for Perovskite Solar Cells Fabrication

Abstract

Developing cost-effective and rational hole transporting materials is critical for fabricating high-performance perovskite solar cells (PSCs) and to promote their commercial endeavor. We have designed and developed pyridine (core) bridging diphenylamine-substituted carbazole (arm) small molecules, named as 2,6PyDANCBZ and 3,5PyDANCBZ. The linking topology of core and arm on their photophysical, thermal, semiconducting and photovoltaic properties were probed systematically. We found that the 2,6PyDANCBZ shows higher mobility and conductivity along with uniform film-forming ability as compared to 3,5PyDANCBZ. The PSCs fabricated with 2,6PyDANCBZ supersede the performance delivered by Spiro-OMeTAD, and importantly also gave improved long-term stability. Our findings put forward small molecules based on core-arm linking topology for cost-effective hole selective layers designing.

Recent Advances in Organic Hole Transporting Materials for Perovskite Solar Cells

“…Later, Ahmad and coworkers developed two HTMs by linking topology of pyridine core and methoxydiphenylamine‐substituted carbazole arm coded as 2,6PyDANCBZ and 3,5PyDANCBZ, aiming to achieve continuous π‐conjugation by dihedral angles between core and arm. [ 41 ] In contrast to the rough 3,5PyDANCBZ surface film with pinholes and voids, the smooth nature of 2,6PyDANCBZ film improves the borderline contact between the perovskite and HTM layer, suppressing the direct contact between back electrode and perovskite and consequently improving the performance of corresponding devices. After implementation of 2,6PyDANCBZ, the champion device efficiency of 17.78% was obtained with a V OC of 1061 mV, a J sc of 22.13 mA cm −2 , and an FF of 0.76, whereas the device with 3,5PyDANCBZ gave a comparatively lower PCE of 15.92%.…”

Efficient Inverted Perovskite Solar Cells with Low Voltage Loss Achieved by a Pyridine‐Based Dopant‐Free Polymer Semiconductor

“…Pyridine is a widely‐used Lewis base type surface passivation molecule due to its ability of passivating under‐coordinated lead ions at the surface of perovskites [50–52] . In addition, it also has been successfully employed as the electron‐acceptor unit to construct donor‐acceptor type HTMs, which can regulate the highest occupied molecular orbital (HOMO) levels and the hole transport ability of resulting HTMs due to intramolecular electron push‐pull effect [53–56] . Therefore, pyridine could be an ideal building block towards high‐performance multifunctional HTMs.…”

“…[50][51][52] In addition, it also has been successfully employed as the electron-acceptor unit to construct donor-acceptor type HTMs,w hich can regulate the highest occupied molecular orbital (HOMO) levels and the hole transport ability of resulting HTMs due to intramolecular electron push-pull effect. [53][54][55][56] Therefore,p yridine could be an ideal building block towards high-performance multifunctional HTMs.…”

Functional Pyrene–Pyridine-Integrated Hole-Transporting Materials for Solution-Processed OLEDs with Reduced Efficiency Roll-Off

“… 48 Moreover, in recent time, rationally functionalized pyridines have been investigated to have good hole extraction and hole-transporting potential, and thus, such materials have been used as efficient hole-transporting materials (HTMs) for optoelectronic applications. 49 − 54 While different types of pyrene and pyridine derivatives have been developed and tested for their potential as HTMs, there has been no report, to our knowledge, on the use of pyridine–pyrene-integrated systems as HTMs for optoelectronics applications.…”