A low band gap conjugated small molecule based on isoindigo flanked with diketopyrrolopyrrole for efficient organic solar cells

作者：Jung Jae Woong^*

来源：Dyes and Pigments, 2017, 137: 512-517.

DOI：10.1016/j.dyepig.2016.10.042

• Isoindigo
• Diketopyrrolopyrrole
• Small molecules
• Organic solar cells

Herein, we report design and synthesis of DPP-Ii-DPP, a conjugated small molecule (SM) composed of central isoindigo flanked with diketopyrrolopyrrole (DPP), for organic solar cell (OSC) application. The DPP-Ii-DPP exhibited broad and intense absorption in 400-800 nm in wavelength with a low optical band gap of 1.46 eV. However, in contrast to common DPP-based SMs with strong electron-donating central moiety, DPP-Ii-DPP exhibited much lowered energy levels (HOMO = -5.56 eV), which is beneficial to achieve high open circuit voltage (V-OC) of the devices. For the purpose to optimize power conversion efficiency (PCE) of OSCs based on DPP-Ii-DPP, the photoactive blend film was treated with thermal/solvent annealing or processing additive. Among which, the device with solvent annealing exhibited an optimized PCE of 5.86% with a Vac of 0.86 V, a J(SC) of 11.75 mA/cm(2) and FF of 0.58. This work shows the potential of DPP-Ii-DPP as a "promising SM-based electron donor materials for efficient OSC5.

• 出版日期2017-2