UNSW’s Dr. Meng Zhang and his co-researchers have made a giant stride towards commercialisation of perovskite solar cells, and a creative artwork depicting their exciting new process has been selected to grace the cover of distinguished journal, Advanced Energy Materials.
Zhang and his co-researchers engineered a new combination of additives that assist the crystallisation process of perovskite in low temperature environments, turning it into a more stable photovoltaic structure with better energy conversion efficiency.
For the perovskite material FAPbI3 to be useful in solar cells, it must change from its photoinactive form, the δ-phase, to the α-phase which is good at absorbing light.
However, the phase transition requires high-temperature treatment (≥150°C) which can cause harmful internal stresses in the material, potentially leading to reduced performance or stability. To counter this, Methylammonium (MA) is often added to regulate the crystallisation process at low temperature (~100°C), but the potential residual MA raises concerns about long term stability.
Dr. Zhang and his team sought a new perovskite crystallisation process. They discovered that by adding two MA-free chemicals, PbCl2 and MPSO, the phase change happens at much lower temperatures (≤80°C). They also found that the resulting perovskite ink is moisture resistant. It demonstrates excellent stability and can be processed in open air environments, without the need for humidity control.
These inks should enable the fabrication of large-area film fabrication under ambient atmosphere conditions which is a crucial step towards the commercialisation of perovskite PV.
The creative cover image of a game of tennis uses a net and ball analogy.
The ball symbolises the process of transforming the perovskite from the stable, photoinactive δ-FAPbI3 phase (yellow side of the court) into the photoactive α-FAPbI3 phase (black side) that is ideal for solar cell applications.
The net symbolises the energy barrier that the perovskite (ball) must overcome to transition from the δ-phase to the α-phase. The helpful ball boys are the additives PbCl2 and MPSO. They lower the net (the energy barrier) to assist the transition.
Perovskite solar cells have the potential for much higher energy efficiencies and lower costs than silicon, but stability and durability issues have so far kept them in the labs, despite the thousands of groups working towards a commercial product.
The commercialisation of perovskite solar cells depends upon the development of moisture resistant perovskite inks that can be processed at low temperatures without additives that threaten their stability. The perovskite inks formed under this methodology should enable the fabrication of large-area film fabrication under ambient atmosphere conditions.
The work was guided by Professor Xiaojing Hao and Professor Martin A Green and is supported by the Australian Centre for Advanced Photovoltaics, and others.
Read the paper.
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