Time-Gated Breath Figures Enable Time-Resolved Analysis of Interfacial Nanorod Growth

Understanding the growth dynamics of semiconductor nanorods remains challenging because most syntheses proceed under continuously reacting conditions, where growth histories collapse into end-point morphologies. Here, we introduce a time-gated breath figure strategy enabled by a two-valve humidity control system that allows interfacial reactions to be discretely initiated and arrested without disrupting template formation. Using CdS as a representative model system, the time-gated breath figure approach enables time-resolved analysis of radial and axial growth evolution during nanorod formation under confined interfacial conditions. The results suggest that nanorod diameters become established at an early stage of interfacial reaction, whereas subsequent reacting time primarily influences axial elongation within a finite temporal window. This temporally decoupled growth behavior is consistent with a distinct growth regime characterized by early radial fixation and temporally limited axial elongation. Such temporally resolved growth evolution has remained difficult to access in conventional syntheses performed under continuously reacting conditions. Beyond providing insight into nanorod growth dynamics, these findings establish a useful framework for understanding interfacial growth under confined conditions and for designing nanorod-embedded porous films based on reacting breath figure processes.