A naphthodithiophene-diketopyrrolopyrrole donor molecule for efficient solution-processed solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic photovoltaics (OPVs) offer a promising alternative to traditional silicon solar cells due to their flexibility and low manufacturing costs.
• Developing efficient and stable donor materials is crucial for advancing OPV technology.
• Small-molecule organic semiconductors are attractive for OPVs due to their defined structures and potential for high charge mobility.

Purpose of the Study:

• To synthesize and characterize a novel naphtho[2,3-b:6,7-b']dithiophene (NDT)-based donor molecule.
• To evaluate the performance of this NDT-based molecule in organic photovoltaics (OPVs).
• To establish a new benchmark for power conversion efficiency (PCE) in small-molecule OPVs using a common electron acceptor.

Main Methods:

• Synthesis of the NDT-based donor molecule, NDT(TDPP)(2).
• Fabrication of organic photovoltaic (OPV) devices using NDT(TDPP)(2) as the donor and PC(61)BM as the electron acceptor.
• Characterization of the synthesized molecule and the fabricated OPV devices, including optical absorption, molecular packing, and charge mobility measurements.

Main Results:

• The NDT(TDPP)(2) molecule exhibits broad, high oscillator strength visible absorption, indicating efficient light harvesting.
• Devices fabricated with NDT(TDPP)(2) and PC(61)BM achieved a power conversion efficiency (PCE) of 4.06 ± 0.06%.
• The NDT(TDPP)(2) molecule demonstrated ordered molecular packing and exceptional hole mobility, contributing to the high device performance.

Conclusions:

• The novel NDT-based donor molecule represents a significant advancement in small-molecule OPV materials.
• The achieved PCE of 4.06% is a record for OPVs utilizing the PC(61)BM electron acceptor.
• The material's optical and electronic properties, including broad absorption and high hole mobility, are key to its high performance in organic photovoltaics.