Organic hole-transporting materials (HTM) have shown excellent ability in achieving high efficiency perovskite solar cells. However, their high cost significantly limits their applications in scaling-up perovskite solar cells. Here, we report an efficient, low-cost HTM, called TAT-^tBuSty, comprising a central triazatruxene moiety with 3 terminal tert-butoxy styrene groups and 3 hexyl side chains on the indole nitrogen. For the first time, we use an inexpensive liquid precursor to attach the donor ligand to the molecule. This enables purification of the HTM using a silica plug and recrystallization without the need for complicated column chromatography, which is typically required to purify solid-precursor-prepared HTMs. We estimate that the cost for the purified TAT-^tBuSty is $69.90 g⁻¹, which is 35% cheaper than the widely-used 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-OMeTAD; ca. $112.05 g⁻¹). Using this low-cost TAT-^tBuSty as the HTM in a caesium-formamidinium mixed-cation perovskite solar cell, we have successfully achieved a champion power conversion efficiency (PCE) of 20.3% (19.4% stabilized efficiency), which is comparable to the efficiency of devices using the reference spiro-OMeTAD HTM. Our work is crucial for up-scaling of next-generation high-performance metal-halide perovskite solar cells.

We report push–pull flavins bearing different donor groups that exhibit high hyperpolarisabilities (β = 355–9550 × 10⁻³⁰ esu) and decomposition temperatures thereby indicating their potential application as non-linear optical device materials.

Thiophene-based semiconductors are amongst the most successful materials in organic electronics. In this contribution, we present the synthesis and characterisation of two thiophene-based macrocycles as well as their evaluation in organic-electronic devices. McT-1 is composed of ten thiophene moieties, whereas in McT-2, four additional electron-deficient benzothiadiazole moieties are incorporated to form a donor–acceptor (D–A) π-system. Red-shifted and broadened absorption spectra as well as more positive redox potentials are observed in McT-2, whereas McT-1 displays a sharper absorption band with a higher extinction coefficient. Macrocycle McT-1 shows emission in the yellow region whereas McT-2 displays emission in the red wavelength region. DFT calculations predict the macrocycles to comprise of mainly the E,E isomers with a near-planar structure, which is further supported by the single crystal X-ray structure for McT-1. Their charge transporting properties are determined by fabricating thin-film OFETs. The photovoltaic properties of McT-1 and McT-2 are also investigated by fabricating bulk heterojunction (BHJ) devices and their potential as photodetectors has been evaluated.

Precursors to three new 3,4-ethylenedioxythiophene (EDOT) incorportaing dyes have been synthesised via a one-pot C–H activation route using N,N-dimethylaniline as a donor group. We have extended this methodology to provide a convenient one-pot route to dye EDOT-Ph. The electrochemical and optical properties of the new dyes have been correlated with IV and EQE data for 1 cm² dye-sensitized solar cell (DSSC) devices prepared using these dyes. The device data show that dye performance is strongly affected by the amount of chenodeoxycholic acid (CDCA) co-sorbent used. The best performance is for EDOT-Ph (η = 4.0%) at 10 mM CDCA compared to (η = 6.0% and η = 5.8%) for N719 and D205 control cells.