Simple, Highly Efficient Vacuum‐Processed Bulk Heterojunction Solar Cells Based on Merocyanine Dyes

Abstract

In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum‐processed small molecule solar cell based on merocyanine dyes – traditional colorants that can easily be mass‐produced and purified – is presented. In the past, merocyanines have been successfully introduced in solution‐processed as well as vacuum‐processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed.

Influence of Solid-State Packing of Dipolar Merocyanine Dyes on Transistor and Solar Cell Performances

“…15 Later on we confirmed our concept with improved materials for both solution-(HB366, 4.5%) 16 as well as vacuum-processed devices (HB194, 5.8%). 17 The groups of Blanchard, Roncali and Wong among others [18][19][20][21][22][23][24] have investigated other types of D-A dyes and pushed 2 solar cell devices based on dipolar D-A molecules even further, reaching PCEs of up to 6.8%. 25 …”

Donor Materials for Organic Solar Cell (OSC)

“…During the device characterization, SM2 displayed a PCE of 4.9 % by simple layer stack [124]. Later in 2011, they introduced MoO 3 as a hole-collecting contact to the devices fabrication, resulting in an increase of V OC from 770 to 970 mV and an enhanced PCE of 6.1 % for SM2 [125].…”

Improvement in the open-circuit voltage of an organic photovoltaic device through selection of a suitable and low-lying highest occupied molecular orbital for the electron donor layer

“…More recently, some D-A structure based materials have been reported to be showing a PCE of more than 3% in vacuumdeposited planar bilayer OPVs. [20][21][22] Hence it is desirable to explore more stable materials, as they may greatly improve the performance of OPV devices.…”