Image: University of Surrey
An international research team under the leadership of the University of Surrey with Imperial College London has identified a strategy to improve both the performance and stability of lead-tin perovskite solar cells, achieving a champion device with 23.2% power-conversion-efficiency, of which it Says that it is one “the best results” achieved with this material and “more importantly, a design strategy that improves the lifespan of these devices by 66%.”
The researchers built the cell with a hole transport layer (HTL) on the basis of pedot: PSS, a polymer that is known for its low costs and easy preparation properties and said solar cells and also multi -function solar cells.
“It is expected that this specific subcel will replace the role of silicon in the current Perovskiet-based tandem and multijunction cells,” said co-racked author Imalka Jayawardena PV Magazine.
The team investigated performance loss and lower stability mechanisms of Pedot: PSS-based perovskiet opto electronics. They noted that amine-containing organic cations pedot de-dope pedot: pss. It can be “partially recovered with thiocyanate additives”, but improvement is at the expense of device stability due to cyanogenic formation of thiocyanate-Jodium interaction, the team noted, is accelerated in the presence of moisture.
“Our work shows that the organic cations can diffuse in pedot: PSS that leads to loss of efficiency,” Jayawardena explains. “We also show that this diffusion process can be illuminated with a thiocyanate additive. However, the thiocyanate can also accelerate the breakdown of the perovskite solar cell in the process of moisture to which we have demonstrated a solution. “
The biggest challenge was to insulate factors that, according to Jayawardena, could mask the actual diffusion and breakdown mechanism.
The team noted that, in the presence of moisture, thiocyanates form cyanogens, which accelerate the breakdown of perovskiet, regardless of the used hole transport layer. It also explained that device efficiency and stability for lead-tin perovskites could be improved under environmental conditions with iodine reduction within the bulk as an important strategy.
“To reduce this demolition route, we include an iodine reduction tool in Lead-Tin PSCs. The resulting devices display an improved electricity conversion efficiency of 23.2%, one of the highest reported for Lead-Tin PSCs, ”the team stated that it resulted in a 66% improvement in the TS80 lifetime under Maximum Power Point -Tracking and ambient circumstances.
In addition, the devices for the Champion laboratory had an open circuit voltage of 0.875 V, a short-circuit density of 31.84 MA CM-2 and a filling factor of 83.23%. “For comparison: an operating device showed a lower efficiency of 21.86%, with a short-circuit current density of 31.53 MA CM-2, an open circuit voltage of 0.852 V and a filling factor of 81.41%,” the researchers said.
Looking ahead, the researchers want to identify stability-enhancing additives for perovskietabsorbers, alternatives to pedot: PSS, while also developing mini modules using green solvents. “At Surrey we are currently performing accelerated stress tests, among other things, demanding circumstances,” said Jayawardena, adding high humidity and temperature tests are planned, as well as an outside test bed to evaluate the team’s mini modules.
