2021 Adv. Mater. (IF 30.849), ASM-OSC with 16.2% PCE & 75.6% FF
Enlitech’s REPS and FTPS systems make Voc-oss analysis of solar cells no longer out of reach!
Advanced Materials (IF 30.849) published a research result in November 2021. Harald Ade of North Carolina State University, Zhixiang Wei of Nanoscience Center and others made the efficiency of all-small-molecule organic solar cells (ASM-OSC) reach 16.2% through the high miscibility of ordered molecular packing.
Compared with polymer solar cells (PSCs), all-small-molecule organic solar cells (ASM-OSCs) composed of small molecule donors and small molecule acceptors can be processed in solution. The relationship between their molecular structures and device performance were even greater and easy to build. In ASM-OSC, high short-circuit current (Jsc) usually uses small phase separation, and high fill factor (FF) is usually achieved in highly ordered stacking systems. However, the two always conflict with each other and restrict Jsc and FF.
In order to alleviate this dilemma, the research team proposed to obtain good miscibility and ordered packing by adjusting the interaction of the same and different molecules. They moved the alkylthiolated side chain in the small molecule donor from the para position to the meta position and developed two new types of small molecule donors: P-PhS and M-PhS. At this time, the surface tension of the donor and the planarity of the molecule were simultaneously enhanced and produced good miscibility and strong self-assembly ability with the acceptor BTP-eC9.
The research results showed that this method realized an optimized form of multi-length-scale domains and highly ordered packing. Analyzed through the Enlitech’s REPS photovoltaic Voc-loss analyzer, FTPS Fourier Transform Photocurrent Spectroscopy system and other instruments, the device exhibited a long carrier lifetime (39.8 μs) and fast charge collection (15.5 ns). Besides, it obtained 16.2% efficiency, 75.6% high FF and 25.4 mA cm-2 Jsc. These results indicate that obtaining good miscibility and high crystallinity at the same time may be a design criterion for improving the performance of ASM-OSC.
a) Electroluminescence quantum efficiency curve; b) highly sensitive EQE spectra for blend films.
Keywords: all-small-molecule organic solar cells, ASM-OSC, Voc-loss analysis, small molecule donors, molecular structure characterization
Article link: https://doi.org/10.1002/adma.202106316