Donor-?-donor type hole transporting materials: marked ?-bridge effects on optoelectronic properties, solid-state structure, and perovskite solar cell efficiency.

ABSTRACT: Donor-?-bridge-donor type oligomers (D-?-D) have been studied intensively as active materials for organic optoelectronic devices. In this study, we introduce three new D-?-D type organic semiconductors incorporating thiophene or thienothiophene with two electron-rich TPA units, which can be easily synthesized from commercially available materials. A thorough comparison of their optoelectronic and structural properties was conducted, revealing the strong influence of the extent of longitudinal ?-bridge conjugation on both the solid structure of the organic semiconductive materials and their photovoltaic performance when applied as hole transporting materials (HTM) in perovskite solar cells. Single-crystal measurements and time-resolved photoluminescence (TRPL) studies indicate that these coplanar donor-?-donor type HTMs could be promising alternatives to state-of-the-art spiro-OMeTAD, due to the multiple intermolecular short contacts as charge transporting channels and efficient charge extraction properties from the perovskite layer. The optimized devices with PEH-9 exhibited an impressive PCE of 16.9% under standard global AM 1.5 illumination with minimized hysteretic behaviour, which is comparable to that of devices using spiro-OMeTAD under similar conditions. Ambient stability after 400 h revealed that 93% of the energy conversion efficiency was retained for PEH-9, indicating that the devices had good long-term stability.

SUBMITTER: Paek S 

PROVIDER: S-EPMC6022229 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature