Pressure effects on interfacial surface contacts and performance of organic solar cells

Abstract

This paper explores the effects of pressure on the interfacial surface contacts and the performance of organic solar cells. A combination of experimental techniques and analytical/computational models is used to study the evolving surface contacts profiles that occur when compliant, semi-rigid and rigid particles are interlocked between adjacent layers in model solar cell structures. The effects of layer surface roughness and interlocked (trapped) particles are also considered along with the effects of surface energy, adhesion energy, and pressure. The results show that increased interfacial contact lengths and decreased void lengths are associated with the application of increased pressure. Increased pressure also results in significant improvements in power conversion efficiency. These improvements in power conversion efficiency are associated with the closure up of micro-and nano-voids due to the application of pressure to layers produced via spin coating and thermal evaporation. The results suggest that pressure-induced contacts can be used to enhance the performance of organic solar cells.

Role of interface properties in organic solar cells: from substrate engineering to bulk-heterojunction interfacial morphology

“…The pressure on the interface contact has an impact on the performance of OSCs. 119 Pressure was applied to the model bilayer and OSC structure using a polydimethylsiloxane (PDMS) stamper. As compliant, semi-rigid and rigid particles interlock between adjacent layers of the model solar cell structure, an evolving surface contact profile occurs (in Fig.…”

“…With the application of the pressure in the out-of-plane direction and perpendicular to the substrate, the bond between the polymer main chains is also elongated in the in-plane direction, thereby forming an on-edge configuration. 119 In addition, the capillary action in the confined mold plays a key role in the phase separation of the film and polymer crystallization. The nanoimprint process can improve the crystallinity and multi-dimensional chain arrangement of the polymer to achieve more effective charge transfer, and allow fine phase separation between the donors and acceptors, thereby promoting exciton dissociation and improving charge transfer excitons.…”

“…Reproduced with permission. 119 Copyright 2017, American Physical Society. (g) Schematic (not to scale) of meniscusguided coating on the IL [EMIM][TFSI] hosted in nanoporous anodized aluminum oxide dynamic template.…”