Green microalgae are promising and sustainable bioenergy and biomass feedstocks, that specifically utilize blue and red light for photosynthesis. Using carbon dots (CDs) to optimize photoluminescence is an attractive strategy for enhancing microalgal bioresource production; however, CD synthesis traditionally requires harsh conditions and laborious procedures. Little research has focused on developing CDs with tunable emission that precisely satisfy photosynthetic requirements. In this work, we directionally prepared non-toxic CDs using a simple method, which could adsorb light at spectra 500-600 nm and emit red light at 580-700 nm. CDs significantly promoted microalgae (Chlorella) growth by similar to 15%. Meanwhile, potential intracellular bioresources, pigments, carbohydrates, proteins, and lipids were generally enhanced. CDs, combined with an extracellular polymeric substance of microalgal cells, served as numerous micro-bulbs for Chlorella irradiation to sustainably provide optimized light. In this context, photosystems I and II were both stimulated. As such, we prepared CDs with tunable emission, which could significantly enhance microalgae and bioresource production. (C) 2020 Elsevier Inc. All rights reserved.