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Conjugated polymers (CPs) offer the potential for sustainable semiconductor devices due to their low cost and inherent molecular self-assembly. Enhanced crystallinity and molecular orientation in thin films of solution-processable CPs have significantly improved organic electronic device performance. In this work, three methods, namely spin coating, dip coating, and unidirectional floating-film transfer method (UFTM), were utilized with their parametric optimization for fabricating RR-P3HT films. These films were then utilized for their characterization via optical and microstructural analysis to elucidate dominant roles of molecular orientation and crystallinity in controlling charge transport in organic field-effect transistors (OFETs). OFETs fabricated by RR-P3HT thin films using spin coating and dip coating displayed field-effect mobility (μ) of 8.0 × 10−4 cm2V−1s−1 and 1.3 × 10−3 cm2V−1s−1, respectively. This two-time enhancement in µ for dip-coated films was attributed to its enhanced crystallinity. Interestingly, UFTM film-based OFETs demonstrated μ of 7.0 × 10−2 cm2V−1s−1, >100 times increment as compared to its spin-coated counterpart. This superior device performance is attributed to the synergistic influence of higher crystallinity and molecular orientation. Since the crystallinity of dip-coated and UFTM-thin films are similar, ~50 times improved µ of UFTM thin films, this suggests a dominant role of molecular orientation as compared to crystallinity in controlling the charge transport.

WN thin films were synthesised on silicon (100) substrate by varying the nitrogen flow rate (NFR) at a substrate temperature of 300°C for the initial 15 min using RF magnetron sputtering. With the increase in NFR from 1.58, 5.29 and 10 sccm (standard cubic centimetres per minute), the FCC β-W2N phase was converted to mixed phases of FCC β-W2N and hexagonal δ-WN, and further to amorphous phases. Likewise, XPS results indicated the presence of W-N phases. In addition, structural and morphological studies confirmed the presence of dense films at 1.58 sccm of NFR with a thickness of 430 nm and a surface roughness of 0.99 ± 0.16 nm. Moreover, the film with β-W2N phase (at 1.58 sccm of N2 flow) exhibited high hardness and elastic modulus values of 28.36 ± 2.57 GPa and 149.72 ± 8.04 GPa, and better scratch resistance with average coefficient of friction (COF) value of 0.303, making it best suitable for hard coating applications. [ABSTRACT FROM AUTHOR]