The versatile photoresponse-turnability of two-dimensional (2D) semiconductors by tuning the gate voltage has shown promising pathways for in-sensor visual processing. However, the current limited dynamic range and slow response speed of the gate-tunable 2D photodetectors inhibit their implementation in challenging lighting conditions. Here, using a facile, efficient, and universal local electrostatic screening strategy, we demonstrate an electrostatic screening enabled single-gate-tunable in-plane homojunction photodiodes with bipolar high dynamic ranges (HDRs) and ultrafast photoresponse based on WSe2. The showcase van der Waals (vdW) stacking of WSe2/PdSe2 in-plane homojunction photodiodes leveraging the efficient band alignment and less interface recombination inherited from vdW nature exhibits a large physical linear dynamic range (LDR) up to 142 dB and an ultrafast response time down to 8 ns. These superior properties ensure the device captures high-precision HDR images and performs in-sensor image processing with low latency. Our results provide an effective strategy for constructing 2D photodetectors with tunable positive/negative responses and high LDRs, which is promising for in-sensor visual processing of scenes with HDR.
