Van der Waals heterojunctions made from two-dimensional materials offer competitive opportunities for designing and implementing multifunctional and high-performance electronic and optoelectronic devices. A pentagonal two-dimensional-layered noble metal transition metal disulfide molecular complex PdSe₂ is used to construct a heterojunction capable of operating at room temperature, which has air stability and high electron field-effect mobility. InSe devices manufactured on rigid SiO₂/Si substrates have a response time of approximately 50 ms, exhibiting long-term stability in optical switches, and can be performed on flexible substrates. Under the appropriate band alignment design of the Schottky junction and heterojunction, the heterostructure comprising PdSe₂ and InSe exhibits a high reverse rectification ratio exceeding 10⁶, ultralow forward current lower than pA at room temperature, and a high current on/off ratio exceeding 10⁸. Therefore, the PdSe₂/InSe van der Waals heterojunction can be used as an ultrasensitive photodetector, exhibiting apparent photovoltaic effects and spectral detection capability. This study provides a new approach to van der Waals integration and design based on two-dimensional materials and energy band alignment technology for photoelectric multifunctional equipment.