Benzodithiophene‐Based, Donor–Acceptor–π–Donor–Acceptor Systems as Hole Transporting Materials for Efficient Perovskite Solar Cells

Abstract

Four new donor-acceptor-π-bridge-accepter-donor hole-transporting materials (HTMs) were developed based on the 2,2'-(4,8-bis(octyloxy)benzo [1,2-b:4,5-b']dithiophene (OBDT) core moiety functionalised with two diphenylamine-based donor units as outlying moieties. The compounds were designed, synthesised and used in perovskite solar cells (PSCs). Each HTM was thoroughly characterized with various spectroscopic techniques, and the surface and cross-sectional morphologies of the thin-film topmost layer, steady-state photoluminescence, hole mobility and PSC efficiency were estimated and correlated with a standard Spiro-OMeTAD HTM. The stabilized photocurrent and power conversion efficiency (PCE) measurements at maximum power point tracking, and J-Voc curves under forward, and reverse bias, were studied. The film of the methylsubstituted derivative provided a very consistent and compact protected layer to the whole perovskite layer, which is the key to the enhancement of the Voc and fill factor (FF). The PSC device based on the methyl derivative as HTM showed a high PCE of 19.07 % (active area 0.42 cm 2 ) which is compared to the SpiroOMeTAD control device (17.90 %; active area 0.42 cm 2 ). Optimized devices retained about 90 % PCE for 60 days, suggesting the reported HTM framework as a promising material for PSC application, considering also that they are tuneable and can be synthesized on a large scale.

Alkylsilyl-substituted benzodithiophene-based small molecules as promising hole-transport materials for perovskite solar cells

“…[15][16][17][18] Thus, S. Pola et al showed recently that BDT-based small molecules with a DA-p-AD structure (donor-acceptor-p-bridge-acceptor-donor, where the p-bridge is a BDT derivative) are promising HTMs for PSCs. 19 Combination of BDT with indole derivatives in DA-p-AD HTMs allowed a high PCE of 19% to be achieved along with the good stability of devices. The group led by Y. Li constructed PSCs with outstanding PCEs of 23-24% by using symmetric or more complex asymmetric DA-p-AD HTMs, where the p-bridge was represented by a uorine-substituted BDT moiety.…”

Governing the emissive properties of 4-aminobiphenyl-2-pyrimidine push–pull systems via the restricted torsion of N,N-disubstituted amino groups

“…KEYWORDS intramolecular charge transfer, donor-acceptor systems, fluorosolvatochromism, photophysical properties, theoretical calculations Introduction Push-pull structures are conjugated organic molecules integrated by electron-donating and electron-withdrawing moieties separated by a π-system, which broadens the charge distribution across the molecule, endowing it with exotic optical and electronic properties (Bureš, 2014). This class of materials has been extensively used as sensitizers in dye-sensitized solar cells (DSSCs) (Verbitskiy et al, 2014;Verbitskiy et al, 2015;Tan et al, 2016;Kozlov et al, 2017;Sun et al, 2018;Verbitskiy et al, 2021b) and hole-transporting materials in perovskite-based solar cells (Maddala et al, 2021;Bouihi et al, 2022;Manda et al, 2022) owing to their high molar absorption coefficient and efficient hole mobility, respectively. Moreover, they can be integrated into organic light-emitting diodes (OLEDs) (Wong et al, 2002;Wu et al, 2002;Nakao et al, 2017;Ryutaro et al, 2018;Verbitskiy et al, 2021a) because of their high fluorescence quantum yields (Φ F ).…”