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Six new hole transporting materials based on commercially available m-MTDATA core were synthesized by introducing different electron donating groups, such as methoxy, ethoxy and dimethylamino. To achieve the target compounds...

Here, we report on three new triphenylamine-based enamines synthesized by condensation of an appropriate primary amine with 2,2-diphenylacetaldehyde and characterized by experimental techniques and density functional theory (DFT) computations. Experimental results allow highlighting attractive properties including solid-state ionization potential in the range of 5.33–5.69 eV in solid-state and hole mobilities exceeding 10 –3 cm 2 /V·s, which are higher than those in spiro-OMeTAD at the same electric fields. DFT-based analysis points to the presence of several conformers close in energy at room temperature. The newly synthesized hole-transporting materials (HTMs) were used in perovskite solar cells and exhibited performances comparable to that of spiro-OMeTAD. The device containing one newly synthesized hole-transporting enamine was characterized by a power conversion efficiency of 18.4%. Our analysis indicates that the perovskite–HTM interface dominates the properties of perovskite solar cells. PL measurements indicate smaller efficiency for perovskite-to-new HTM hole transfer as compared to spiro-OMeTAD. Nevertheless, the comparable power conversion efficiencies and simple synthesis of the new compounds make them attractive candidates for utilization in perovskite solar cells.

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Replacement of hole‐transporting materials (HTM) for additive‐free perovskite solar cells (PSCs) is an urgent issue. In this work, three new derivatives of dibenzothiophene with methoxyphenyl, trimethoxyphenyl, carbazole moieties are synthesized as hole‐transporting materials for PSCs. The hole density dynamics and hole transporting properties of synthesized dibenzothiophene derivatives are investigated by combination of the charge extraction by linearly increasing voltage (CELIV) and time‐of‐flight (TOF) techniques. The TOF hole mobility (μh) of one compound reaches the highest value of 4.2 × 10−3 cm2 V−1s−1 at an electric field of 2.5 × 105 V cm−1, however additive‐free layers in PSCs did not show the best performance. Instead, the PSC efficiency is determined by a trade‐off between the hole‐mobility properties and the “effective” hole recombination rate kB ranging 0.5–40.3 ms−1 as determined by means of the CELIV method. The best hole extraction properties are observed for a compound with μh of 9.45 × 10−4 cm2 V−1s−1 and kB of 11.8 ms−1 which is coherent with its lowest energetic disorder σ of 78.2 meV. Having both appropriate hole density dynamics and hole‐transporting properties, hole‐transporting layer of that compound allows to reach PCE of 20.9% for additive‐free PSC, which is among the state‐of‐art values for devices with undoped HTM.