Fig. 4: Incremental afterglow display based on DRTP.

a Screen printing process of anti-counterfeiting pattern containing the information of the 80th anniversary for Heilongjiang University (left), and the changing process of emission patterns under 365 nm excitation at 0 s and at several representative stages at 30 ms and 0.5–2.0 s after UV turn-off (right). DCzSBr, DCzDBr and DCzSBrSP were used to prepare the pattern, which are indicated at the left of their corresponding patterns. The emerging of DCzSBrSP based Chinese characters can be distinguished between 30 ms and 0.5 s. b Nonlinear time-encoded security application exampled with a password panel based on DCzDBr, DCzSBr and DCzSBrSP. A thermally activated delayed fluorescence (TADF) molecular DMAC-DPS with microsecond-level lifetime was used to initiate emission pattern under UV excitation. After UV turn-off, three different RTP patterns can be distinguished: (i) instant information at 30 ms formed by IRTP of DCzSBr and DCzDBr; (ii) delayed information 1 at 0.15 s formed by IRTP of DCzSBr and DCzDBr and DRTP of DCzSBrSP; (iii) delayed information 2 after 0.5 s formed by IRTP of DCzSBr and DRTP of DCzSBrSP.