Free Radical-Resistant Carbon Dots for Bulky Luminescent Solar Concentrators with High Optical Efficiency

The use of environment-friendly carbon dots (CDs) for preparing luminescent solar concentrators (LSCs) is a hot topic. Because of the low extinction coefficient of CDs and the thin film thickness, most reported LSCs fabricated by a CD-containing film on a matrix have low optical efficiency below 5%. Bulky CD-based LSCs are expected to be used as a solution because the increased thickness can compensate for the low extinction coefficient of CDs. However, the challenge is the quenched fluorescence of CDs by free radicals during polymerization. Herein, we reported free radical-resistant fluorescent solid-state CDs, which were synthesized by citric acid and N-[3-(trimethoxysilyl)propyl]ethylenedi-amine (DAMO). The diamine group on DAMO is important to obtain bright CDs, while siloxane groups on DAMO facilitate the formation of silica shells outside CDs. After being exposed to free radicals, as-prepared silica shell-capped CDs maintain 88.2% of the original fluorescence intensity. Furthermore, free radical-resistant CDs are used to fabricate LSCs by coupling solar cells on the side of CD–polymer composite prepared by bulk polymerization. For a typical device with the dimension of 2 cm × 2 cm × 0.5 cm, the optical efficiency is up to 9.3%, which remains constant under sunlight irradiation during the monitoring period of 65 days.