Hole transporting materials for perovskite solar cells: molecular versus polymeric carbazole-based derivatives

Abstract

Designing organic hole transporting materials (HTMs) for stable perovskite photovoltaic devices remains a great challenge. Herein, we have prepared two small carbazole-based HTMs bearing a polymerizable double bond and one of the corresponding polymers. All compounds can be easily synthetized by a short procedure from largely available commercial products. These compounds have thermal, morphological, optical and electrochemical properties suitable for an application in perovskite solar cells. The side chains at the N-positon on the carbazole have a negligible influence on the opto-electrochemical properties. However, the thermal properties differ largely between the monomer and its corresponding polymer. While these materials have the same photovoltaic performance, the polymeric HTM led to more stable devices. This illustrates the higher thermal stability of polymeric HTM versus its corresponding monomer.

Carbazole Electroactive Amorphous Molecular Material: Molecular Design, Synthesis, Characterization and Application in Perovskite Solar Cells

“…On the second one, only the glass transition was recorded at the glass transition's temperature (Tg) of 62.5 °C. This value is slightly higher than that of its 3,6-isomer reported earlier (Tg = 61 °C) [17] due to its higher steric hindrance of the 2,7-disubstituted molecule.…”

“…In solution, iDM1 photoluminescence is centered at the wavelength of 419 nm. A Stock shift of 28 nm was recorded, which is somehow smaller than that of its 3,6-isomer reported earlier [17]. In thin film, the absorption slightly redshifts to 397 nm, due to the steric hindrance of iDM1 avoiding molecular aggregation in the solid state.…”

“…Energies 2020, 13, x FOR PEER REVIEW 2 of 10 carbazole derivatives occupy an important place thanks to their unique properties [13,14]. We have shown that carbazole is an excellent platform to design not only HTMs for solid-state dye-sensitized solar cells (DSSCs) [15] and PSCs [16][17][18][19] but also as photoinitiators for photopolymerization and 3D printing technique [20][21][22][23]. Herein, we prepare a novel molecular glass denoted as iDM1 (Scheme 1) and test it as HTM in PSCs.…”

“…The different steps for preparing perovskite photovoltaic devices (substrate etching, cleaning and preparation of FTO/bl-TiO 2 /meso-TiO 2 layer, preparation and deposition of the hole transporting layer, thermal evaporation of gold back electrode and J-V characterizations) were followed from our previous optimized procedure [17][18][19]27]. In this work, different perovskite layers, named MAPI(2), MAPI(1)-SOF and FAMA were elaborated by two-step sequential and one-step deposition techniques by spin coating.…”

“…On the other hand, it provides a good interaction with the perovskite surface [25]. The 4-vinylbenzyl chain at the 9-position of the carbazole offer the possibility of transforming iDM1 into its corresponding polymer for a possibly monomer vs. polymer comparative study [17].…”