D-π-A-Type Pyrazolo[1,5-<i>a</i>]pyrimidine-Based Hole-Transporting Materials for Perovskite Solar Cells: Effect of the Functionalization Position
Fatiha Bouihi,
Bruno Schmaltz,
Fabrice Mathevet,
David Kreher,
Jérôme Faure-Vincent,
Ceren Yildirim,
Ahmed Elhakmaoui,
Johann Bouclé,
Mohamed Akssira,
François Tran-Van,
Mohamed Abarbri
Affiliations
Fatiha Bouihi
Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l’Energie (EA 6299), Université de Tours, Parc de Grandmont, 37200 Tours, France
Bruno Schmaltz
Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l’Energie (EA 6299), Université de Tours, Parc de Grandmont, 37200 Tours, France
Fabrice Mathevet
Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
David Kreher
CNRS, Institut Parisien de Chimie Moléculaire, IPCM, Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
Jérôme Faure-Vincent
CEA, CNRS, IRIG-SyMMES, Université Grenoble-Alpes, 38000 Grenoble, France
Ceren Yildirim
CNRS, XLIM, UMR 7252, Université de Limoges, 87000 Limoges, France
Ahmed Elhakmaoui
Laboratoire de Chimie Physique et Biotechnologies des Biomolécules et des Matériaux (LCP2BM), Faculté des Sciences et Techniques de Mohammedia, Université Hassan II de Casablanca, BP 146, Mohammedia 28800, Morocco
Johann Bouclé
CNRS, XLIM, UMR 7252, Université de Limoges, 87000 Limoges, France
Mohamed Akssira
Laboratoire de Chimie Physique et Biotechnologies des Biomolécules et des Matériaux (LCP2BM), Faculté des Sciences et Techniques de Mohammedia, Université Hassan II de Casablanca, BP 146, Mohammedia 28800, Morocco
François Tran-Van
Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l’Energie (EA 6299), Université de Tours, Parc de Grandmont, 37200 Tours, France
Mohamed Abarbri
Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l’Energie (EA 6299), Université de Tours, Parc de Grandmont, 37200 Tours, France
Donor–acceptor (D–A) small molecules are regarded as promising hole-transporting materials for perovskite solar cells (PSCs) due to their tunable optoelectronic properties. This paper reports the design, synthesis and characterization of three novel isomeric D-π-A small molecules PY1, PY2 and PY3. The chemical structures of the molecules consist of a pyrazolo[1,5-a]pyrimidine acceptor core functionalized with one 3,6-bis(4,4′-dimethoxydiphenylamino)carbazole (3,6-CzDMPA) donor moiety via a phenyl π-spacer at the 3, 5 and 7 positions, respectively. The isolated compounds possess suitable energy levels, sufficient thermal stability (Td > 400 °C), molecular glass behavior with Tg values in the range of 127–136 °C slightly higher than that of the reference material Spiro-OMeTAD (126 °C) and acceptable hydrophobicity. Undoped PY1 demonstrates the highest hole mobility (3 × 10−6 cm2 V−1 s−1) compared to PY2 and PY3 (1.3 × 10−6 cm2 V−1 s−1). The whole isomers were incorporated as doped HTMs in planar n-i-p PSCs based on double cation perovskite FA0.85Cs0.15Pb(I0.85Br0.15)3. The non-optimized device fabricated using PY1 exhibited a power conversion efficiency (PCE) of 12.41%, similar to that obtained using the reference, Spiro-OMeTAD, which demonstrated a maximum PCE of 12.58% under the same conditions. The PY2 and PY3 materials demonstrated slightly lower performance in device configuration, with relatively moderate PCEs of 10.21% and 10.82%, respectively, and slight hysteresis behavior (−0.01 and 0.02). The preliminary stability testing of PSCs is also described. The PY1-based device exhibited better stability than the device using Spiro-OMeTAD, which could be related to its slightly superior hydrophobic character preventing water diffusion into the perovskite layer.
