The highest record of organic photoelectric conversion efficiency of solar cells

[China Instrument Network Instrument R&D] Recently, Professor Chen Yongsheng of the School of Chemistry at Nankai University has made breakthroughs in the research of organic solar cells. They used a complementary light-absorbing strategy of oligomer materials to construct a stacked organic solar cell device with broad spectral absorption characteristics, achieving a photoelectric conversion efficiency of 12.7%, which is currently reported in the literature for the photoelectric conversion of organic/polymer solar cells. The highest record of efficiency.

Figure 1 a) Donor material molecular structure b) Front and back cell materials Film absorption spectra c) Laminated organic photovoltaic device structure d) Laminated cell JV curve

Organic solar cells are organic, including high-molecular materials with photosensitizing properties, as semiconductor materials, generate voltages through photovoltaic effect, and then form currents to realize solar power generation. As one of the effective ways to solve the problems of environmental pollution and energy crisis, it is far superior to traditional solar cells in terms of low cost, high flexibility, simple process, and environmental friendliness.

However, since the birth of the first organic solar cell device in 1958, how to improve the photoelectric conversion efficiency has always been a key problem for scientists. This problem also directly determines whether organic solar cells can be taken out of the laboratory and widely used in human production and life.

“As an emerging frontier research field, the dramatic increase in energy conversion efficiency of organic solar cells has been mainly attributed to the design and development of photoactive layer materials and the continuous optimization of device structures in recent years,” said Chen Yongsheng.

Over the years, the Chen Yongsheng team has conducted a systematic and systematic study on the selection and construction process of organic photovoltaic device materials, developed a series of highly efficient oligomer-based molecular active layer materials that can be solution-treated, and achieved over 10% in 2015. Photoelectric conversion efficiency (J. Am. Chem. Soc., 2015, 137, 3886-3893.).

Considering the requirements of industrialization, the use of active materials with different spectral absorption ranges for the preparation of stacked photovoltaic devices is one of the effective strategies for further improving the photoelectric conversion efficiency. Based on this idea, team researchers prepared oligomerized molecules/polymers as front and back cells, and obtained stacked-layer organic photovoltaic devices with energy conversion efficiencies exceeding 11% (Adv. Mater., 2016, 28, 7008–7012.) .

Recently, the Chen Yongsheng team cooperated with the research team of South China University of Technology to use BDT-based oligomers and porphyrin-based small molecular materials with good complementary absorption in the visible and near-infrared regions as donor materials for front and rear cells, respectively. Highly efficient organic solar devices have been prepared by solution processing methods compatible with industrial production. After the optimization of the process, the verification efficiency of 12.7% was finally achieved (Nature Photon., 2016, published online.).

According to the research team of the team, according to the relevant design principles, through the further optimization of materials and devices, the device's indicators including photoelectric conversion efficiency still have much room for improvement. It is expected that in the near future, more than 15% of photoelectric conversion efficiency will be obtained.

"Next, we will mainly solve the problem of battery life, and further increase the efficiency of energy conversion. I believe that the organic solar cell from the real application of the laboratory, the realization of the dream of commercial production will become a reality in the near future." Chen Yongsheng said.

It is understood that this research has received strong support from the Ministry of Science and Technology, the National Natural Science Foundation of China, Tianjin Science and Technology Commission and Nankai University.

(Original title: The Nankai team has achieved a major breakthrough in organic solar cell research by achieving a photoelectric conversion efficiency of 12.7%)