An organic field effect transistor comprising a double layer consisting of i) a first layer comprising a percolating network of single-walled carbon nanotubes having a content of at least 95% by weight of semiconducting single-walled carbon nanotubes, and ii) a second layer comprising an organic semiconducting material; wherein the first layer consists of a percolating network of single-walled carbon nanotubes; and wherein the organic semiconducting material is at least one diketopyrrolopyrrole-based material, wherein the diketopyrrolopyrrole-based material is a diketopyrrolopyrrole-based polymer consisting of units of formula wherein R 1 is C 6-30 -alkyl, n and m are independently 0 or 1, provided n and m are not both 0, and Ar 1 and Ar 2 are independently L 1 and L 2 are independently selected from the group consisting of ED wherein Ar 3 is at each occurrence arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C 1-30 -alkyl, C 2-30 -alkenyl, C 2-30 -alkynyl, O-C 1-30 -alkyl, aryl or heteroaryl, which C 1-30 -alkyl, C 2-30 -alkenyl, C 2-30 -alkynyl, O-C 1-30 -alkyl, aryl and heteroaryl can be substituted with one or more C 1-20 -alkyl, O-C 1-20 -alkyl or phenyl; and wherein adjacent Ar 3 can be connected via a CR b R b , SiR b R b or GeR b R b linker, wherein R b is at each occurrence H, C 1-30 -alkyl or aryl, which C 1-30 -alkyl and aryl can be substituted with one or more C 1-20 -alkyl, O-C 1-20 -alkyl or phenyl, b is at each occurrence an integer from 1 to 8, and Ar 4 is at each occurrence aryl or heteroaryl, wherein aryl and heteroaryl can be substituted with one or more C 1-30 -alkyl, O-C 1-30 -alkyl or phenyl, which phenyl can be substituted with C 1-20 -alkyl or O-C 1-20 -alkyl. i) a first layer comprising a percolating network of single-walled carbon nanotubes having a content of at least 95% by weight of semiconducting single-walled carbon nanotubes, and ii) a second layer comprising an organic semiconducting material; wherein the first layer consists of a percolating network of single-walled carbon nanotubes; and wherein the organic semiconducting material is at least one diketopyrrolopyrrole-based material, wherein the diketopyrrolopyrrole-based material is a diketopyrrolopyrrole-based polymer consisting of units of formula wherein R 1 is C 6-30 -alkyl, n and m are independently 0 or 1, provided n and m are not both 0, and Ar 1 and Ar 2 are independently L 1 and L 2 are independently selected from the group consisting of ED wherein Ar 3 is at each occurrence arylene or heteroarylene, wherein arylene and heteroarylene can be substituted with one or more C 1-30 -alkyl, C 2-30 -alkenyl, C 2-30 -alkynyl, O-C 1-30 -alkyl, aryl or heteroaryl, which C 1-30 -alkyl, C 2-30 -alkenyl, C 2-30 -alkynyl, O-C 1-30 -alkyl, aryl and heteroaryl can be substituted with one or more C 1-20 -alkyl, O-C 1-20 -alkyl or phenyl; and wherein adjacent Ar 3 can be connected via a CR b R b , SiR b R b or GeR b R b linker, wherein R b is at each occurrence H, C 1-30 -alkyl or aryl, which C 1-30 -alkyl and aryl can be substituted with one or more C 1-20 -alkyl, O-C 1-20 -alkyl or phenyl, b is at each occurrence an integer from 1 to 8, and Ar 4 is at each occurrence aryl or heteroaryl, wherein aryl and heteroaryl can be substituted with one or more C 1-30 -alkyl, O-C 1-30 -alkyl or phenyl, which phenyl can be substituted with C 1-20 -alkyl or O-C 1-20 -alkyl. <EOS>