Breaking the 1250 nm Barrier: A Computational Approach to Light Upconversion via Triplet–Triplet Annihilation in the Silica Telecom Band

The 1250–1675 nm region is the spectral range exploited in modern telecommunications and quantum networks because of the high transparency of silica-based nanofibers. Nevertheless, the low efficiency of detectors and sensors in that region requires light upconversion (UC). This is achieved with inorganic dopants, often based on rare-earth elements or metal nanoparticles that are characterized by a low chemical flexibility besides sustainability issues. Triplet–triplet annihilation upconversion (TTA-UC) is a process that exploits as emitters organic molecules that would remove or mitigate these limitations. Nevertheless, no TTA-UC emitters have been reported to be able to absorb in the telecom region and very few in the region at wavelengths longer than 1000 nm. Here, we used Kohn–Sham density functional calculations to tune the triplet energy of tetracene, the parent molecule of a class of emitters for infrared light UC. We highlight three organic molecules, each with an existing synthetic procedure, as promising near-infrared (NIR) TTA-UC annihilators. Additionally, we computationally predict 5,12-bis(N,N-diaminobenzene)tetracene as an emitter for TTA-UC of light beyond 1250 nm. These findings pave the way for the design and development of organic molecules for upconverting the telecom-band NIR light.