A Self‐Assembled Small‐Molecule‐Based Hole‐Transporting Material for Inverted Perovskite Solar Cells

Abstract

Hybrid organic–inorganic perovskite solar cells have recently emerged as one of the most promising low‐cost photovoltaic technologies. The remarkable progress of perovskite photovoltaics is closely related to advances in interfacial engineering and development of charge selective interlayers. Herein, we present the synthesis and characterization of a fused azapolyheteroaromatic small molecule, namely anthradi‐7‐azaindole (ADAI), with outstanding performance as a hole‐transporting layer in perovskite solar cells with inverted architecture. Its molecular arrangement, induced by hydrogen‐bond‐directed self‐assembly, favors a suitable morphology of the perovskite layer, reducing the effects of recombination as revealed by light intensity dependence, photoluminescence, and electroluminescence studies.

NiOx‐Seeded Self‐Assembled Monolayers as Highly Hole‐Selective Passivating Contacts for Efficient Inverted Perovskite Solar Cells

“…[ 22 ] After this work, they further designed a series of SAMs with carbazole bodies and phosphonic acid (PA) anchoring groups as HTLs for wide‐bandgap PVK solar cells as well as PVK‐based tandem devices. Other SAMs such as Zn phthalocyanine (TT1), [ 27 ] anthradi‐7‐azaindole (ADAI), [ 28 ] and 4′‐(3,6‐bis(2,4‐dimethoxyphenyl)‐9H‐carbazol‐9‐yl)‐[1,1′‐biphenyl]‐4‐carboxylic acid (EADR04) [ 29 ] were also synthesized for HTLs in inverted PVK solar cells. However, the deposition of well‐ordered SAMs is still difficult due to its sensitive nature toward the chemical feature of the substrate surface, the binding affinity of the anchoring group, and the geometry of the spacer group.…”

Hydrogen-Bonded Dopant-Free Hole Transport Material Enables Efficient and Stable Inverted Perovskite Solar Cells

“…To the best of our knowledge, there are only two articles that claim the application of hydrogen bonding functionalized HTMs in PSCs. 24,25 Kaneko et al proposed small molecular dopant-free HTMs to fabricate n-i-p type PSCs with PCE of 14.5 %, but the authors did not focus on the inverted p-i-n structure. In addition, they synthesized the molecules containing multi-large size alkyl chains to enhance the solubility of the small molecules.…”

Effect of molecular geometry and extended conjugation on the performance of hydrogen-bonded semiconductors in organic thin-film field-effect transistors

“…73 Initially, the corresponding diamines, namely p-phenylenediamine, 1,5-diaminonaphthalene, 1,5-diaminoanthracene 74 and 1,6-diaminopyrene, 75 reacted with 2,3-dichloropyridine using standard palladium-catalysed conditions for a Buchwald-Hartwig reaction. 76 The resulting bis(pyridyl) aromatic diamines, 1, 2, 3 and 4, led to the respective polyheteroaromatic products BDAI, NDAI, ADAI 70 and PDAI, via photochemical carbon-carbon coupling in good yields. All the intermediate and final products were structurally characterised by NMR spectroscopy and mass spectrometry (Fig.…”

“…The structural particularity of these compounds lies in the fusion of the 7-azaindole building block that enables the integration of the hydrogen bonding sites within the conjugated skeleton itself. [70][71][72] Additionally, the resulting fused polyheteroaromatic molecules present a fully conjugated structure that differs from the conjugation of some of the above-mentioned indigoid systems. Interestingly, the use of hydrogen-bonded rigid centrosymmetric structures can induce a supramolecular expansion of the p-surface that also favours a concomitant p-stacking.…”