Tailoring organic heterojunction interfaces in bilayer polymer photovoltaic devices

Abstract

In an ideal model, a p-n junction is formed by two stacked slabs of semiconductors. Although the construction of actual devices is generally more complex, we show that such a simple method can in fact be applied to the formation of organic heterojunctions. Two films of the organic semiconductors poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) can be connected by a simple film-transfer method without disturbing their flat surfaces. Each film can further be modified with a surface-segregated monolayer to tune the strength and direction of the surface dipole moment. Using this method, we fabricated bilayer organic photovoltaic devices with interfacial dipole moments that were selected to align the energy levels at the heterojunction. The open-circuit voltages of the P3HT/PCBM devices could be tuned over a wide range between 0.3 and 0.95 V, indicating that, even if the same combination of bulk materials is used, the interfacial properties drastically alter the performance of organic photovoltaic devices.

Efficient Inverted Polymer Solar Cells with Directly Patterned Active Layer and Silver Back Grating

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Structure‐Property Optimizations in Donor Polymers via Electronics, Substituents, and Side Chains Toward High Efficiency Solar Cells

“…There are other important issues regarding side chains, which are beyond the scope of this discussion but nevertheless merit further consideration, including but not limited to side chain density [ 94 ] and fl uorinated side chains for use as interfacial additive layers. [ 95 ] …”

Molecular interfaces for plasmonic hot electron photovoltaics

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