Charge trap materials that can store carriers efficiently and controllably are desired for memory applications. Two-dimensional (2D) materials are promising for highly compacted and reliable memory mainly due to their ease of constructing atomically uniform interfaces, however, remain unexplored as being charge trap media. Here we discover that 2D semiconducting PbI 2 is an excellent charge trap material for non-volatile memory and artificial synapses. It is simple to construct PbI 2 -based charge trap devices since no complicated synthesis or additional defect manufacturing are required. As a demonstration, MoS 2 /PbI 2 device exhibits a large memory window of 120 V, fast write speed of 5 μs, high on-off ratio around 10 6 , multilevel memory of over 8 distinct states, high reliability with endurance up to 10 4 cycles and retention over 1.2×10 4 seconds. We envision that PbI 2 with ionic activity caused by the natively formed iodine vacancies is unique to combine with unlimited 2D materials for versatile van der Waals devices with high-integration and multifunctionality. This article is protected by copyright. All rights reserved.