Perovskite solar cells (PSCs) currently reach high efficiencies, while their insufficient stability remains an obstacle to their technological commercialization. The introduction of hole-transport materials (HTMs) into the device structure is a key approach for enhancing the efficiency and stability of devices. However, currently, the influence of the HTM structure or properties on the characteristics and operational stability of PSCs remains insufficiently studied. Herein, we present four novel push-pull small molecules, H1-4, with alternating thiophene and benzothiadiazole or fluorine-loaded benzothiadiazole units, which contain branched and linear alkyl chains in the different positions of terminal thiophenes to evaluate the impact of HTM structure on PSC performance. It is demonstrated that minor changes in the structure of HTMs significantly influence their behavior in thin films. In particular, H3 organizes into highly ordered lamellar structures in thin films, which proves to be crucial in boosting the efficiency and stability of PSCs. The presented results shed light on the crucial role of the HTM structure and the morphology of films in the performance of PSCs.

There is a resurgence in the use of triphenylamine-based donor materials (TPA) in the field of perovskite photovoltaics. This work presents the synthesis of two novel conjugated small molecules (CSM's), TPA-t and TPA-t EH, which are functionalized with triisopropylsilyl groups and 2-ethylhexyl side chains. These molecules show promise as hole transport materials, which possess high hole mobilities of 1.5 × 10-4 and 2.9 × 10-3 cm2 V−1 s-1 due to self-organization. TPA-t and TPA-t EH possess HOMO energy levels at -5.38 and -5.31 eV, which is well-aligned with valence band of standard perovskite MAPbI3.This resulted in outstanding open-circuit voltages of 1100 and 1080 mV. TPA-based molecules were investigated as HTLs in n-i-p PSCs without additional doping and enabled high efficiency (17.4 %) same as for devices with state-of-the-art polytriarylamine (PTAA) HTL. The obtained results suggest that developed materials could potentially compete with PTAA when further material structure modification.