Fig. 1. Categories of persistently luminescent materials and related applications

Fig. 2. Number of literatures on persistently luminescent materials in different years, and number of literatures on four major disciplines in different time periods (data are retrieved from web of science and China Knowledge Network and searched with the above mentioned keywords of long-lived luminescence, long persistent luminescence, and persistent phosphors, and their search results are analyzed). (a) Number of literatures on persistently luminescent materials in different years; (b) number of literatures on four major disciplines in different time periods