Nangong University made a breakthrough in the preparation of perovskite film

Renewable energy such as photovoltaic is gradually becoming the main force to achieve the "dual carbon" strategy, and perovskite photovoltaic is one of the important directions of the current development of
the photovoltaic field due to its outstanding characteristics such as excellent performance and low cost.
On November 10, the scientific research team of Nanjing University of Technology made a breakthrough in the preparation of perovskite films, which will help its photovoltaic industrialization
.
The scientific research results "Perovskite solar cells based on screen printing films" were published
online in Nature.

"Compared with other film manufacturing technologies, screen printing technology has outstanding advantages
such as low cost, high utilization rate of raw materials and simple preparation process.
" Talking about the innovation of this scientific research achievement, Professor Chen Yonghua, the project leader and deputy dean of the School of Flexible Electronics (Future Technology) of Nanjing University of Technology, said that perovskite film deposition has many methods
such as spin coating, scraping, inkjet printing and screen printing.
Among them, screen printing technology is unique, with simple process, high efficiency, easy patterning, low cost and other outstanding advantages, and is considered to be the ideal technology
for the industrialization of perovskite solar cells.
Screen printing technology can prepare each layer of perovskite device film, but screen printing perovskite photoactive layer has never been realized
.
"Our research group has achieved innovative results in two main aspects, one is to realize the controllable preparation of screen printing perovskite ink, and the other is to prepare efficient and stable all-screen printing devices
.
"

"The preparation of perovskite active layer by screen printing has always been a problem in the scientific community, and the existing low-viscosity organic solvent system is difficult to apply to screen printing to prepare perovskite films, which limits the development of
low-cost screen printing perovskite photovoltaic devices.
" Chen Changshun, a student at Nanjing University of Technology, said that similar to ink printing test papers, the ink is too thin and non-sticky, and the words in the stereotype are difficult to be clearly presented on the paper, and it is difficult for low-viscosity solvents to print perovskite films with a thickness of 400~500 nanometers, which limits the development of
low-cost screen printing perovskite photovoltaic devices.

How to solve the problem of preparing perovskite active layer films from screen printing? For the first time, the research team proposed an ionic liquid perovskite printing ink
with controllable viscosity, adjustable composition and air stability.
"We creatively prepared long-term stable and viscous reliable perovskite printing inks from ionic liquid methylamine acetate, enabling screen printing and pattern control over film thickness, area and pattern control
on different substrates.
" Chen Jianxin, a student at Nanjing University of Technology, said
.

"All-screen printed perovskite devices are 'hardcore' technologies
that help the industrialization of perovskite.
" Chen Yonghua added that the five or six procedures in the preparation process of traditional perovskite photovoltaic devices need to correspond to five or six devices, but through the dynamic regulation of screen printing films and device structure optimization, we have prepared all-screen printed perovskite photovoltaic devices, successfully realizing "one pot stew", one device to solve all functional layer preparation
。 According to Han Huchen, a student at Nanjing University of Technology, the team developed screen-printed perovskite photovoltaic devices with an efficiency of 20.
52%, fully screen-printed perovskite photovoltaic devices with 14.
98% and all-screen-printed perovskite photovoltaic modules with an efficiency of 11.
80%, and the unpackaged devices maintained their initial efficiency of 96.
75%
after 300 hours of constant illumination at the maximum power point 。 The experimental results show that the perovskite film used for screen printing patterning achieves a printing rate of more than 20 cm/s and a raw material utilization rate close to 100%, and the morphology
of the perovskite film is accurately controlled by the phase transfer mode of "point-line-surface".
"At present, the experimental results can prepare a square high-performance film with a side length of 15 cm, and the next step is to prepare a film
with a side length of 50 cm.
" Chen Yonghua said
.

According to Huang Wei, an academician of the Chinese Academy of Sciences, the perovskite photovoltaic industry has been attracting attention as a hot research field in renewable energy
.
The research team of Nanjing University of Technology has been deeply engaged in this field for many years, and the relevant research results were reported in Science magazine in March 2021, which solved the "sensitive constitution" of perovskite with unstable performance, moisture intolerance, and need to "survive" in inert gases by using ionic liquid membrane making, expanding its environmental adaptability
.
Now, they have solved their photovoltaic industry problems
through screen printing.
Fast, low-cost and efficient perovskite materials are expected to empower economic and social construction and development
.