Publication date: 4th October 2024
The introduction of self-assembled monolayer (SAM) hole transporting materials (HTMs) made a significant contribution towards development of p-i-n architecture perovskite solar cells (PSCs). Carbazole-based derivative V1036 was one of the first SAM HTMs to be successfully used instead of standard PTAA. Although it demonstrated slightly lower efficiency (17.8 %) compared to PTAA (19.2 %), it was evident that monolayer can be efficient compared to the polymeric films of regular thickness [1]. Not long after, V1036 structure was optimized, simplified and its analogues 2PACz and MeO-2PACz were introduced. These small but important structural changes resulted in an increase in p-i-n PSC performance, as 2PACz and MeO-2PACz exhibited PCEs of 20.8 % and 20.2 % respectively, higher than that of PTAA (18.9 %) [2]. Combined with conformal coverage, minimal parasitic absorption and material consumption, SAM HTMs became an important research subject for optoelectronic applications, such as organic photovoltaics, perovskite/silicon tandems or organic light-emitting diodes [3-5]. In this research, new SAM HTMs were synthesized and investigated as 2PACz alternatives to further broaden the scope of possible applications. Two main strategies for structural modifications were applied: selection of different chromophores and incorporation of different functional groups. New SAM materials have been successfully used to construct devices such as p-i-n PSCs, bulk heterojunction organic photovoltaics, organic light-emitting diodes and sensors.