Triphenylamine–Thienothiophene Organic Charge‐Transport Molecular Materials: Effect of Substitution Pattern on their Thermal, Photoelectrochemical, and Photovoltaic Properties

Abstract

Two readily accessible thienothiophene-triphenylamine charge-transport materials have been synthesized by simply varying the substitution pattern of the triphenylamine groups on a central thienothiophene π-linker. The impact of the substitution pattern on the thermal, photoelectrochemical, and photovoltaic properties of these materials was evaluated and, based on theoretical and experimental studies, we found that the isomer in which the triphenylamine groups were located at the 2,5-positions of the thienothiophene core (TT-2,5-TPA) had better π-conjugation than the 3,6-isomer (TT-3,6-TPA). Whilst the thermal, morphological, and hydrophobic properties of the two materials were similar, their optoelectrochemical and photovoltaic properties were noticeably impacted. When applied as hole-transport materials in hybrid perovskite solar cells, the 2,5-isomer exhibited a power-conversion efficiency of 13.6 %, much higher than that of its 3,6-counterpart (0.7 %) under the same standard conditions.

A Bifunctional Bulky Thienothiophene Derivative; Synthesis, Electronic‐Optical Properties and OLED Applications

“…Although the device efficiencies are lower, the obtained EL spectrum of TT-TPA-TPE3 is slightly blue shifted compared to the TTs with no TPA-TPE units. [6][7][8][9][10][11][12][13] The color coordinates of TT-TPA-TPE3 are in the greenish blue region according to the CIE color space chromaticity diagram.…”

“…Maximum electroluminescence wavelengths (488 and 491 nm) of the devices I and II were found to be closer to each other, respectively (Figure 7). Although the device efficiencies are lower, the obtained EL spectrum of TT‐TPA‐TPE3 is slightly blue shifted compared to the TTs with no TPA‐TPE units [6–13] . The color coordinates of TT‐TPA‐TPE3 are in the greenish blue region according to the CIE color space chromaticity diagram.…”

“…Organic fluorophores, having triphenylamine (TPA) derivatives, have drawn a special interest owing to their high emission guest efficiency as well as their high thermal stability in host systems. They are widely used as hole‐ and electron‐transporters, emitting layer for OLEDs and charge transporting materials [8,9] . Fluorescent triphenylamine in solution, which is generally used as a good electron donor in organic material systems, becomes less emissive or even non‐emissive in solid state due to aggregation caused quenching (ACQ) [10–15] .…”

“…They are widely used as hole-and electron-transporters, emitting layer for OLEDs and charge transporting materials. [8,9] Fluorescent triphenylamine in solution, which is generally used as a good electron donor in organic material systems, becomes less emissive or even non-emissive in solid state due to aggregation caused quenching (ACQ). [10][11][12][13][14][15] Moreover, TPA and its fluorophores are expected to produce highly functional materials, synchronously achieving color and emission dual switching, beneficial for the development of both color and emission mode images.…”

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

“…So fabrication of their amorphous thin film stable above ambient temperature required meticulously engineered small conjugated molecules [6]. Among the different HTM families (such as thiophene [7], fused thiophene [8,9], furan [10], acridine [11], trizatruxenes [12], etc.) carbazole derivatives occupy an important place thanks to their unique properties [13,14].…”