Wearable solar-powered clothing, solar energy vehicle and solar power consumer electronics are dreams of current scientists. In particular, dye‐sensitized solar cells (DSSC) has great potential, but on their way to commercialization and mass production, there are hurdles of durability, material utilization rate, technology utilization rate and cell encapsulation.

Compared with commonly-seen, mass-production crystalline silicon solar cells, DSSC doesn't need semi-conductor manufacturing processes. It is easily made, and its cost is low. With dyeing materials, it can capture sunlight and transfer electrons. Its substrate can use flexible material to develop wearable devices, which can be achieved via simple coating.

However, organic material's photo-electricity properties are worse than that of crystalline silicon. Organic material's structure will be destroyed by ultraviolet (UV) rays. Thus, its developmental progress only remains in the labs. Even though quite some researches gradually solve these issues, the in-consistency issue still exists.

For flexible DSSC, currently the research team from Aalto University in Finland and University of Montreal in Canada focus on flexible DSSC's latest development and how to break through the status quo, in order to achieve mass production. The researchers believe that by using roll-to-roll manufacturing process, DSSC can be commercialized. In particular, ink-jet printing can accurately insert dye and electrolyte components, so in the manufacturing process, ink-jet printing has a great developmental potential.

There are hurdles to overcome on the way of mass production for flexible cell encapsulation. If the encapsulation is not sufficiently-sealed, the liquid electrolyte might leak out or the impurities might leak in. Either way remarkably shortens the life span of the cell.

New joining technology among cell substrate is necessary. Because traditional glass-frit process only fits for rigid devices, flexible cells will need a new joining process.

In addition, solar cell's life span requires lasting materials. Kati Miettunen, the researcher of Aalto University in Finland, expressed that flexible solar cell usually is made with metals or plastics. However, metals might get corroded, and plastics might be permeated by water or impurities.

For environmental protection, more-stable flexible substrates should be developed in the future. They should be price-friendly and less environmental impacts. Bio-materials or a hybrid material with wood pulp might be used. Wood pulp is a sustainable material for flexible cell substrate. This research is recently published on Wiley Online Library.

(Article by Daisy Chuang; Photo Credit: Aalto University in Finland)

Reference:
•    Challenges for mass-production of flexible solar cells: durability and environmental impact