Prof. Herman began his speech by explaining the definition of a film. A film is a material that has a very thin thickness that is deposited onto another material. Thin films can be found in everyday life, although they often go unnoticed. One example is eyeglasses. Prof. Herman explained that in the 1960s, people usually had to remove their glasses when taking photos because the lenses reflected light and disrupted the image quality. By coating eyeglass lenses with thin films, people today can keep their glasses on and still get good photos.

Prof. Herman then mentioned that the fabrication method determines how a thin-film material can be applied. Thin films can modify the properties of the materials they coat. For example, reflective eyeglass lenses can be transformed into anti-reflective lenses through thin-film coatings. His experience studying in Japan gave him valuable insight into various film fabrication methods.

“From what I learned and later explored through research with my students, I began thinking about developing a new method that could overcome the challenges in existing fabrication methods,” he said.

The organic material selected for the research was Disperse Red 1, a molecule with one end acting as an electron donor and the other as an electron acceptor, allowing electrons to flow through the molecule. This structure gives it potential as a nonlinear optical material, making it promising for advanced fabrication technologies.

Prof. Herman’s research focused on developing a method that can overcome the limitations of existing techniques. In the spin-coating method, a homogeneous thin film can be produced, but the molecules are randomly oriented, resulting in non-optimal performance. Another method, the Langmuir–Blodgett (LB) technique, uses amphiphilic molecules, which have one end that interacts with water and another that does not. When distributed on a water surface, these molecules naturally orient themselves according to their affinity for water. After the layer is compressed onto a substrate, a thin film is formed. However, the limitation of this method is its dependence on water or other liquids during fabrication. In contrast, optical and electronic manufacturing processes in industry generally rely on dry processes that do not involve liquids. Meanwhile, the Physical Vapor Deposition (PVD) method does not require water, but its level of control is less effective, making organic molecules more susceptible to damage.

In Indonesia, Prof. Herman developed the Electric Field Assisted Physical Vapor Deposition (EFA-PVD) method. In this technique, an external electric field is applied to orient the Disperse Red 1 molecules, allowing them to attach to the substrate. The principle is based on evaporating the molecules under vacuum conditions and directing them with an external electric field so that their orientation can be precisely controlled.

According to Prof. Herman’s research findings, the EFA-PVD method successfully produces thin films with stable molecular arrangements comparable to those achieved through the Langmuir–Blodgett method, but without the need for water. As a result, thin films fabricated using this technique have significant potential for applications in various fields. These include anti-reflective coatings to enhance light absorption and upconversion layers to broaden the absorption spectrum of solar cells, the development of miniaturized optical devices, and biosensors for detecting biological molecules.

“In the future, if we continue to develop this technology, it also has the potential to increase the reputation of Indonesian research on the global stage,” Prof. Herman concluded at the end of his speech.

Reporter: Kayla Vajira Susanto (Microbiology, 2023)