Fabrication and studies of highly efficient non-fullerene organic solar cells

Abstract

Organic solar cells (OSC) technology is regarded as a great potential to solve the currently pressing energy crisis. It is because OSCs have the potential to fabricate large-area solution- processed low cost solar cells. However, in order to achieve this goal, the power conversion efficiency (PCE) must be increased further. The most important advantage of organic solar cell is the highly tunable optoelectronic properties achieved by changing the chemical structure of the organic molecules. After years of research, accumulated experience has already inspired the design of new materials for ideal device performance. One of the central and easy strategies for material chemists is to modify the existing high-performance materials. Numerous cases have proven that this way can retain the desired properties of the original structure and some improvements are shown for the device performance. In the field of OSC, the predominantly used acceptor is the fullerene derivative PC₇₁BM. The desirable electron mobility and ultrafast charge transfer property makes PC₇₁BM an ideal material for OSCs. However, the major drawback of PC₇₁BM is the high cost, which will in turn increase the manufacturing cost of the device. In order to tackle this problem, non-fullerene molecular acceptors are being developed rapidly for their comparable mobility but a much lower cost. In this study, a high performance non-fullerene acceptor ITIC was taken as the model for modifications and two novel acceptors 2FID-IDTT and 4FID-IDTT are being synthesized and single junction OSCs are fabricated to study its optoelectronic properties. These two acceptors could achieve relatively high efficiencies (8.9% and 7.8% respectively) with a medium-bandgap polymer PffBT-2DT which is a high-performance polymer in the fullerene-based systems. This work demonstrates that the modification strategy is a successful method for achieving high performance material for OSC applications.

Date of Award	2017
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology