4.1 Film deposition methods
The morphology can be significantly influenced by the deposition method used to film processing.[88] Different deposition methods, generally including spin-coating, blade-coating and slot-die (Figure 2), can lead to different structures and packing arrangements of the molecules, which can affect the device performance. For example, spin-coating spreads solution on the substrate then quickly shakes off the solution by the centrifugal force, which can form a relatively smooth and uniform film with small crystalline domains.[89] Blade-coating and slot-die use the shear force formed by bending liquid surface to coat the solution on the substrate, which have a certain induction effect on the aggregation and arrangement of solute molecules.[90, 91] In addition, there are some new film-forming methods, such as meniscus-assisted-coating (Figure 2d).