Researchers review recent progress in room-temperature organophosphorus materials toward application

Organic materials with room temperature phosphorus emissions (RTP) have attracted wide attention due to extraordinary properties including long lifetime, large Stokes shift, response to catalysts, etc., and showing bright prospects in broad fields. However, the energy of the excited state of the organic phosphorus is readily consumed by thermal radiation and collision deactivation.

Therefore, many design strategies such as creating a solid environment through crystallization and supramolecular assembly are used to improve the luminescent properties of RTP materials by restricting non-radiative transition, enhancing crossover between systems, etc.

A team of scientists summarizes recent progress in organic RTP materials from the perspective of practical applications including luminescence and display, environmental detection, and bioimaging. Based on their work, the requirements of organic RTP materials for different applications are summarized, which may bring enlightenment to the future applied research of RTP materials. This review has been published in the journal Industrial chemistry and materials.

Organic light-emitting diodes (OLEDs) have shown excellent performance on displays recently, while only 25% of the single excitons in fluorescent materials can be used for light emission. Therefore, harvesting single excitons and triple excitons to achieve 100% theoretical intrinsic quantum efficiency makes phosphorescent materials attractive.

“Related scientific researchers have designed several organic light-emitting diodes based on RTP with high external quantum efficiency using various strategies, which far exceed the theoretical limit of 5% for typical fluorescent materials,” said Ma, a professor at East China University of Sciences. Technology, China.

Due to the ultraviolet radiation and the different lifetime of RTP emissions, anti-counterfeiting or data encryption based on RTP materials has become a popular and popular application. In addition to simple anti-counterfeiting and data encryption based on UV light actuation, the different ages of RTP materials provide a feasible way to achieve multiple anti-counterfeiting or data encryption using time-resolution techniques.

Besides, chemical-responsive RTP is also a potential way to achieve multiple anti-counterfeiting. In addition to the aforementioned applications, RTP materials have also been studied for two rare but meaningful applications, namely latent fingerprint printing and visualization, due to their unique luminescent properties.

“As we all know, many factors affect the luminescence properties of RTP materials, such as oxygen, temperature, etc.,” Ma said. “So RTP-based chemical sensors are also an indispensable research direction, which can produce practical applications in environmental detection.”

The ternary spin property of ground-state oxygen makes it easy for O₂ To quench the triplet excitons of RTP materials, which makes RTP materials ideal candidates for O₂ a statement. In general, both the intensity and lifetime of decreasing phosphorus can be used to achieve quantitative detection of oxygen.

Temperature is also an important external environmental factor to influence RTP emissions because higher temperature will promote non-radiative transition, thus corresponding RTP materials are developed for temperature sensing. In addition, the quenching effect of small organic molecules on RTP emission makes chemical sensors based on RTP materials possible.

Optical imaging plays an important role in biomedical and clinical research. Compared with fluorescence, RTP has a longer lifetime at a longer wavelength which is beneficial for eliminating the interference of background fluorescence and scattered light and obtaining a higher signal-to-noise ratio (SBR). Although RTP materials have many advantages in bioimaging, non-radioactive decay and quenchers in aqueous solutions seriously hinder their practical application.

The researchers innovatively proposed a supramolecular self-assembly strategy and top-down nanoparticle formulation to achieve stable phosphorylation at room temperature in aqueous solution. Therefore, the researchers not only succeeded in building near-infrared phosphor materials with high precision and deep penetration, but also developed RTP materials with long wavelength excitation and phosphor emission simultaneously, which effectively avoided UV damage to living organisms. .

These works show huge potential application value in biological imaging.

Although room temperature organophosphorus materials generated by different strategies have been widely used in various fields due to different luminescence properties, there is still a huge research space for the fabrication of excellent applied RTP materials. Therefore, the team also discusses how to overcome the challenges and possibilities of phosphorous materials.

To obtain efficient organic light-emitting diodes, phosphorescent materials need to meet the characteristics of high quantum yield and short lifetime, while anti-counterfeiting and cryptographic RTP materials often require rich luminous colors and act differently with UV excitation. Application in biological imaging requires that RTP materials have longer wavelengths and lifetimes to eliminate fluorescent background interference and obtain a higher signal-to-noise ratio.

Moreover, the scope of application should be expanded due to the extraordinary optical properties of RTP materials. Further exploration of RTP materials will not only contribute to a deeper understanding of photoluminescence, but will also enhance the practical application of photovoltaic functional materials in our lives.