Study On Interface Modification And Active Layer Optimization Of Organic Solar Cell Device

In this paper, the main work is the optimization of organic solar cell device and its performance study, and specific work can be divided into two parts:(1) the study of buffer layer for improving device performance and stability;(2) the effect of active layer optimization and donor molecular structure on device performance. Abstracts of every part are presented as following:Easily prepared and stable solution-processed carbon dots(C Ds) have been used and systematically investigated as the electron transport layers(ETLs) for both small- molecule and polymer based solar cells. Significantly enhanced device performance and lifetime were observed. The enhanced performance was mainly driven by the improvements of the short circuit current(Jsc) and the fill factor(FF), caused by decreasing the work function of Al electrode and series resistance, increasing shunt resistances, and balancing electron and hole mobility. In addition, lifetimes of the devices with CDs as the ETLs were also significantly improved, due to the much better air-stability of CD material compared to LiF as the ETLs.We used DIN3TC16 Cz and DIN3TC17 Cz as the donor materials, which was just different alkyl side chain. Without any post processing, the OPV device based on DIN3TC16 C z:PC71BM exhibited power conversion efficiency(PC E) of 1.27%, and the performance of device with thermal annealing was significantly improved 5.5%. However, the device based on DIN3TC17 C z:PC71BM with solvent vapor annealing exhibited PCE of 6.46%, compared to 2.94% without any post processing. The reasons to improve the performance of device were mainly due to the active layer morphology had the appropriate degree of phase separation and interpenetrating network structure. As for the different optimized conditions, the reason was mainly due to the different alkyl side chain made molecular film- forming properties and molecule packing different.