[1]Benzothieno[3,2‐b][1]benzothiophene‐Phthalocyanine Derivatives: A Subclass of Solution‐Processable Electron‐Rich Hole Transport Materials

The [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) planar system was used to functionalize the phthalocyanine ring aiming at synthesizing novel electron‐rich π‐conjugated macrocycles. The resulting ZnPc−BTBT and ZnPc−(BTBT)4 derivatives are the first two examples of a phthalocyanine subclass having potential use as solution‐processable p‐type organic semiconductors. In particular, the combination of experimental characterizations and theoretical calculations suggests compatible energy level alignments with mixed halide hybrid perovskite‐based devices. Furthermore, ZnPc−(BTBT)4 features a high aggregation tendency, a useful tool to design compact molecular films. When tested as hole transport materials in perovskite solar cells under 100 mA cm−2 standard AM 1.5G solar illumination, ZnPc−(BTBT)4 gave power conversion efficiencies as high as 14.13 %, irrespective of the doping process generally required to achieve high photovoltaic performances. This work is a first step toward a new phthalocyanine core engineerization to obtain robust, yet more efficient and cost‐effective materials for organic electronics and optoelectronics. Ready to use: The phthalocyanine ring was functionalized with benzothienobenzothiophene moieties to synthesize two solution‐processable p‐type macrocyclic semiconductors and to investigate their chemical, optical and electrochemical properties from an experimental and theoretical point of view. Their implementation as hole transporters in mixed‐ion perovskite solar cells successfully gave power conversion efficiencies up to 14.13 % even in undoped devices.