Spectrally selective quantum dot laminated glass for photonic modulation and climate regulation in greenhouses

Abstract

The spectral and thermal environment in greenhouses is critical for optimizing crop performance, particularly during low-light winter periods. This study evaluated laminated glass integrated with CuInS₂/ZnS quantum dots (QDs) that passively convert ultraviolet and blue photons into orange-red light (590–620 nm), enhancing the spectral quality of transmitted sunlight without requiring active energy input. Compared to a control glass, the QD-glazing increased relative red photon flux by 29% and increased the Red:Blue ratio by 57%, with negligible losses in total PAR (photosynthetically active radiation). Experimental trials conducted from January to February demonstrated that the QD-glazed greenhouse maintained a higher internal air temperature, averaging 0.68 °C warmer than the control. Root zone (nutrient solution) temperature also exhibited consistent thermal advantages, averaging 1–2 °C higher under the QD glazing, contributing to enhanced nutrient uptake. Vapor pressure deficit was elevated in the QD greenhouse during daylight hours, reflecting increased evaporative demand aligned with higher photosynthetic activity. Despite slightly lower DLI (Daily Light Integral) values, QD-treated lettuce exhibited a 37.8% increase in fresh biomass yield and a 41% improvement in light use efficiency, demonstrating that enhanced spectral quality and early-day thermal buffering can significantly boost physiological performance. Notably, concentrations of key macro-nutrients (N, P, K, Ca, Mg, S) and micro-nutrients (Zn, Cu) were significantly higher under QD treatment, indicating enhanced mineral uptake. These results underscore the potential of spectrally selective QD-glazing as a passive, energy-free solution for optimizing greenhouse microclimate and supporting resilient, winter-season crop production. The findings highlight a promising pathway toward climate-smart greenhouse envelopes that integrate photonics with sustainable food and energy strategies.