Increased Efficiency of Organic Solar Cells by Seeded Control of the Molecular Morphology in the Active Layer

Abstract

The performance of non‐fullerene, polymer bulk heterojunction (BHJ) organic photovoltaic devices has a significant correlation with the molecular morphology of the donor and acceptor. The authors show that small organic molecules coordinated to a metal oxide, an electron transport seed layer (ETSL), can profoundly modify the donor:acceptor molecular morphology of inverted organic photovoltaic (OPV) devices. Using grazing incidence wide angle X‐ray scattering (GIWAXS), the authors show that a PTB7‐Th:IEICO‐4F BHJ active layer has a higher degree of face‐on molecular alignment on ETSL‐1 (biphenyl‐4,4′‐dicarboxylic acid, coordinated to ZnO), whilst for naphthalene‐2,6‐dicarboxylic acid coordinated to ZnO (ETSL‐2), it is reduced. Devices of PTB7‐Th:IEICO‐4F BHJ prepared on ETSL‐1 had a 19.91% increase in the average power conversion efficiency (PCE), a 1.56% increase in the fill factor (FF), and a 16.66 ± 0.2% enhancement in the short circuit current density. The observed improvements are believed to be due to significant modifications to the oxide‐BHJ interfacial region of ETSL‐1, namely the elimination of nano‐ridges and defect centers, along with an enhanced wettability. These factors can be correlated with the enhanced device performances, leading to the conclusion that the modulation of the molecular morphology of donor:acceptor blends by ETSL‐1 has a broad impact on improving OPV cell efficiencies.

Solution-Processed Bilayered ZnO Electron Transport Layer for Efficient Inverted Non-Fullerene Organic Solar Cells

“…In addition, CN was added at a concentration of 0.5 vol%. The resultant solution was mechanically stirred in a glovebox at room temperature for 12 h. Spin coating was used to apply the PTB7-Th:IEICO-4F solution onto the substrate at 3000 RPM for 60 s. The coated substrate was then subjected to thermal annealing at 100 • C for 10 min [34,48].…”

Advances in organic photovoltaic cells: a comprehensive review of materials, technologies, and performance

“…Plasmonic nanoparticles, such as gold or silver, can be used to enhance the absorption of light through the excitation of surface plasmon resonance, which can conne and concentrate electromagnetic elds in the active layer. 104,105 In conclusion, the absorption of light is a fundamental process in OPV cells, which is strongly inuenced by the properties of the organic semiconducting materials and the morphology of the active layer. Researchers are continuing to develop new materials and strategies to improve light absorption and increase the efficiency of OPV cells.…”

Environmentally friendly cathode interlayer modification on edible bio‐acids with enhanced electron extraction and improved power conversion efficiency

“…In the past few decades, OSCs have experienced tremendous development. Substantial efforts have been devoted in the material design, process optimization and interfacial engineering 1–3 . Its power conversion efficiency (PCE) has increased from 0.95% of Tang's first OSC to over 19% 4–6 .…”