Light-Induced Charge Accumulation in PTCDI/Pentacene/Ag(111) Heterojunctions

Chemistry

Alberto Morgante¹  Martina Dell’Angela¹  Albano Cossaro¹  Roberto Costantini¹ 

[1] CNR-IOM Laboratorio TASC, SS 14 Km 163.5, I-34149 Trieste, Italy;

关键词: organic heterojunction;    pump–probe photoemission;    exciton dynamics;    transient energy level alignment;    interface dipole;   

DOI  :  10.3390/chemistry3030053

来源: DOAJ

【 摘 要 】

The incorporation of singlet fission (SF) chromophores in solar cells is expected to bring significant increases in the power conversion efficiency thanks to multiexciton generation. However, efficient charge generation in the device is determined by the energy level alignment (ELA) between the active materials, which should favor exciton transport and separation under illumination. By combining ultraviolet photoemission spectroscopy and optical differential reflectance measurements, we determine the ELA in a prototypical SF heterojunction between pentacene (Pc) and perylene-tetracarboxylic-diimide (PTCDI) grown on Ag(111). Time-resolved X-ray photoelectron spectroscopy on such a system reveals light-induced modifications of the ELA; by measuring the transient shift of the core level photoemission lines we observe an accumulation of long-lived holes in the PTCDI within the first hundred picoseconds after the optical pump.

【 授权许可】

Unknown