ION MODULATED ORGANIC TRANSISTORS - Doria

Nikolai Kaihovirta3. RESULTS AND DISCUSSIONS3. RESULTS AND DISCUSSIONSThis chapter is divided into five sections. Each section presents the mainresults and conclusions for respective paper that is covered in this thesis.The all-printed HIFET is presented in Section 3.1, with particular focus onthe roughness of the used plastic substrate (Paper 1). The concept ofutilizing ion-conducting membranes for manufacturing electrolyte gatedOFETs (MemFETs) is demonstrated in Section 3.2 (Paper 2). In Section 3.3,the ion-conducting membranes are further introduced in all-polymerECTs (Paper 3). Section 3.4 emphasizes the various deteriorating effectscaused by the hydrous solid electrolytes on the OFET-behavior (Paper 4).Moreover, the idea of using sterically hindered phenolic antioxidants inorder to inhibit device degradation is motivated in Section 3.5 (Paper 5).3.1 Absence of Substrate Roughness Effects inElectrolyte Gated OFETsThe work evolved from the experiments on reverse gravure coating ofboth P3HT and PVP onto plastic substrates [54]. It was noted that arougher plastic substrate (Mylar A, root mean square (RMS) roughness =25 – 50 nm) was better suited than the smoother PET 505 (RMS roughness= 4 – 6 nm), for coating the second layer (PVP) without removing anddeteriorating the first layer (P3HT). For a conventional OFET, anincreased interfacial roughness will significantly alter the electronictransport in the active channel [51, 55-58]. However, for the all-printedHIFET, the I-V analysis did not reveal such defects albeit the activechannel became rougher (Figure 3.1). Consequently, the target for thiswork was to point at the difference between the electrolyte gated OFET(HIFET) and the OFET when changing the plastic substrate from thesmoother PET 505 to the rougher Mylar A. Additionally, a few possibleexplanations to the observed differences were discussed.21