Photoelectronic　sensors,　such　as　phototransistors,　photoelectronic　vision　sensors,　and　photoelectronic　memory　elements　based　on　low-dimensional　nanomaterials　and　their　hybrid　structures,　have　received　considerable　attention　for　their　unique　structure　and　characteristics.　Most　studies　on　photoconductance　sensors　focus　on　positive　photoconductivity　(PPC);　however,　rare　cases　exist　in　which　the　conductivity　decreases　under　light　exposure.　Such　cases　are　known　as　negative　photoconductivity　(NPC).　The　integration　of　NPC　and　PPC　has　garnered　significant　interest　for　its　switchable　memorized　electron　transport　mechanism,　thus　paving　a　novel　way　for　the　creation　of　nonvolatile　memories,　photoelectric　logic　gates,　and　neuromorphic　computing　systems.　To　deepen　our　understanding　of　NPC-based　photoelectric　sensors,　we　focus　primarily　on　the　basic　mechanics　of　NPC　effects　and　explore　the　related　materials,　structures,　properties,　and　applications.　Then,　we　highlight　the　modulation　techniques　for　achieving　NPC　and　PPC　switching　and　discuss　the　most　promising　logic　and　memory　applications　by　integrating　the　NPC　and　PPC　effects.　Furthermore,　this　study　addresses　key　challenges　in　research　on　nanomaterials　that　exhibit　NPC　effects,　aiming　to　inspire　further　exploration　of　novel,　high-performance,　and　stable　photoelectric　sensors.　©　2024　IEEE.