Investigation on graphene growth by roll-to-roll chemical vapor deposition

Both batch-to-batch(B2 B)and roll-to-roll(R2 R)processes can be used for mass production of graphene films.Because of the simplicity of equipment,the B2 B process is more commonly used in laboratory research.In contrast,the R2 R process is more industrially preferred because it is easier to automate and more compatible with the subsequent transfer process.Up to now,the research on R2 R process has mainly focused on the design of the reactor or the loading configuration,but the in-depth understanding on the growth kinetics is lack.In this paper,we investigated the evolution of graphene growth and revealed that the graphene domain density grown by the R2 R process was larger than that by the B2 B process with the same reaction parameters,which was attributed to different reaction profiles between the two processes.Furthermore,the defective graphene could be healed with elongated reaction time.With the optimized R2 R process,graphene films with quality comparable to those grown by conventional B2 B process could be achieved.Our research will promote the development of the mass-production technique for graphene films.

Flexible perovskite solar cells:Materials and devices

Flexible perovskite solar cells(FPSCs)are supposed to play an important role in the commercialization of perovskite solar cells due to their unique properties,such as high efficiency,thin thickness and being compatible with roll to roll(R2R)process for mass production.At present,deformable and lightweight FPSCs have been successfully prepared and applied as power supply by integrating with different wearable and portable electronics,which opens a niche market for photovoltaics.In this mini review,we will introduce the recent progress of FPSCs from the aspect of small-area flexible devices,R2R processed devices with large scale and emerging flexible cells with deformability and stretchability.Finally,conclusion and outlook are provided.