Theoretical analysis and the morphology control of vertical phase segregation in high-efficiency polymer/fullerene solar cells

Abstract

The morphology control and optimization in the film-forming process and nanoscale phase separation of donor/acceptor interpenetrating networks played an important role in improving the performance of organic solar cells. Vertical phase separation was defined as an inhomogeneous distribution or concentration gradient of polymer/fullerene blends in the spin-coated film, due to the surface energy of the respective components and their interaction with the substrate or the intermediate buffer layers. In this report, we demonstrated, in detail, the theory of vertical phase separation morphology and control of conventional structure solar cells and inverted configuration solar cells, including the choice of solvents and the drying rate, the surface energy control, thermal annealing, as well as external electric field. In particular, we first proposed internal electronic field model of vertical phase separation and revealed the internal rules and organic semiconductor physics and its mechanism for improving the device efficiency and stability.

Fabrication Processes to Generate Concentration Gradients in Polymer Solar Cell Active Layers

“…Both theoretical and experimental results have demonstrated that ED–EA vertical concentration gradients will play a major role in the production of high efficiency devices, especially when a layered structure is obtained composed of an ED-rich layer on the anode side, an EA-rich layer on the cathode side and an intermixed layer sandwiched between the two first layers [ 23 , 24 ]. However, it is not always easy to fabricate such active layers, especially in inverted device architectures.…”

Exfoliated graphite nanoplatelets/poly(arylene ether nitrile) nanocomposites

“…Carbon-based polymer nanocomposites, which have received considerable attention from academia and industry, are used to enhance the mechanical and barrier properties of materials and/or to introduce new functionalities such as magnetic and electrical properties. [1][2][3] In the past decades, numerous carbon nanomaterials-including zero-dimensional fullerene, 4 one-dimensional carbon nanotubes, [5][6][7] and two-dimensional graphene [8][9][10] -have been widely adopted because of their excellent mechanical properties, thermal stability, super electric properties, and so on. Although many achievements have been made in the area of carbon-based polymer composites, there are still several drawbacks in practical applications.…”