Van der Waals heterojunctions show immense potential in electronic and optoelectronic applications. In this talk, a vdW heterojunction-based all-two-dimensional transistor will be discussed. The all-2D transistor shows no surface roughness scattering, a property hitherto unforeseen in its three dimensional counterparts. A dual-gated MoS₂/WSe₂ vdW heterojunction diode can be tuned to operate in various diode operation regimes. The same device operates as a forward rectifying diode as well as a tunnel diode, merely by application of gate voltage. The first observation of gate controlled band to band tunneling in semiconducting 2D heterostructures was made here, enhancing the prospects of using vdW heterojunctions for low power electronic applications. A 2D/2D tunnel field effect transistor with WSe₂ and SnSe₂ will be discussed. VdW heterojunctions with graphene/h-BN/graphene show negative differential resistance, which can be used in analog applications, such as in oscillators and amplifiers. Also, a graphene/insulator/graphene heterostructure demonstrates resistive switching and can be used to make ultra-low power resistive memories. Thus, vdW heterojunctions display a new paradigm of materials innovation to sustain the aggressive improvement of electronics for the continued betterment of human lives.