Nicholas Rolston, Stanford University
An interesting talk about the completely different aspect of perovskite solar cell was given by Nicholas Rolston - the thermomechanical property of perovskite solar cell. Using the Double Cantilever Beam (DCB) test, Nicholas was able to measure the fracture energy (Gc) of different perovskite cells. To have a rough idea about the Gc of different widely used materials: the Gc of silica glass is about 10 J/m2; the Gc of the Si - the dominant material in the solar industry is about 100 J/m2; the Gc of organic photovoltaic is about 5 J/m2. Not surprising but disappointing, the Gc of perovskite is only 0.1-1 J/m2, this is among the weakest values being measured. The value is similar to the commonly used table salt. By studying different cell architectures, Nicholas pointed out that the electron and hole transport layers in perovskite cells are even weaker than the perovskite active layer. The Gc also depend on the deposition method of perovskite, the exposure condition in term of humidity and heat, the molecular additive and etc. The study has opened another grand challenge for the perovskite researchers on the roadmap to commercialization.