Enhancing the performance of solar cells with 'graphene armor'

• A group of scientists, connected with UNIST has actually thought of a novel electrode that might substantially boost the security of perovskite solar cells (PSCs), one of the most promising prospect for the next generation solar cells because of their low cost and high power conversion effectiveness. This is due to the fact that putting a protection layer in between the metal-based electrode as well as the perovskite movie can stop metal-induced deterioration and that graphene, thus a layer, can effectively subdue the diffusion of steels and also halide ions.

This innovation was led by Professor Hyesung Park as well as his research study group in the School of Energy and Chemical Engineering at UNIST. In their work, the study group created a flexible metal grid-based hybrid electrode system by utilizing a Cu grid-embedded polyimide (CEP) movie with a graphene sheet as the security layer (GCEP), which exhibited high electrical conductivity, exceptional chemical stability and mechanical sturdiness. The development shows the critical duty of graphene as a protection layer to avoid metal-induced deterioration and also halide diffusion in between the electrode as well as perovskite layer.

Steel oxide-based electrodes (ITOs) have actually been made use of as conventional clear carrying out electrodes, however their inflexibility triggers them to be easily broken or fractured, for this reason making them unsuitable to wearable device applications. Specifically, the significant barrier to the metal-based clear conductive electrodes (TCE) application in PSCs is the deterioration caused by the interdiffusion of metals and also halide ions in between the metal electrode and the perovskite layer.

The researchers resolved the problem by putting a graphene sheet as the security layer at the metal electrode/perovskite layer user interface. Graphene has high electric conductivity, which allows electrons to relocate conveniently via it. Nonetheless, the exceptional impermeability of graphene avoids the permeation of also the tiniest particle.

" Graphene can be an efficient diffusion barrier if incorporated with metal nanostructures having impressive impermeability to steel and halide ion diffusion at the metal electrode/perovskite layer user interface, boosted fee collection across deep space spacings of the metal nanostructures, marginal loss of optical passage as a security layer as a result of its high optical openness, and also enhancement of the mechanical durability of the crossbreed electrode," kept in mind the research team.

The researchers used this transparent as well as adaptable hybrid electrode to produce versatile metal TCE-based PSCs, attaining good chemical and also mechanical stability. This device achieved a high PCE (16.4%) equivalent to that of its ITO-based inflexible counterpart (17.5%). They likewise verified the function of the graphene layer in guaranteeing the chemical stability of the solar cells by protecting against steel and also halide ion interdiffusion. Furthermore, the GCEP electrode enhanced the PSC photostability by blocking the ultraviolet (UV) and also near-UV light. It additionally kept over 97.5% of the first efficiency even after 1,000 hrs. Furthermore, after 5,000 flexing tests, it revealed outstanding mechanical toughness such as preserving 94% of the preliminary effectiveness, and hence it applied to next-generation wearable tools.

" This paper shows that inserting a protection layer in between the metal-based electrode as well as the perovskite film could avoid metal-induced deterioration and that graphene, therefore a layer, can successfully suppress the diffusion of steels as well as halide ions," claims Gyujeong Jeong (Combined M.S/ Ph.D. program of Energy and Chemical Engineering, UNISt), the very first author of the study.

" The brand-new approach has dramatically improved both the effectiveness as well as stability of PSCs," claims Professor Park. "This work provides an efficient approach to design mechanically as well as chemically robust ITO-free metal-assisted TCE systems in PSCs."