## 3 Polystyrene in TIPS Pentacene Crystallization
### High Molecular Weight PS (Greater than 250k)
After etching the TIPS pentacene semiconductor by using the hexane solvent, the mixture film comprising PS revealed a smooth surface, whereas the counterpart with PMMA exhibited rough protruding polymeric structures. Thin film transistors comprising the polymer additive showed negligible hysteresis, which indicated the absence of trap centers on the charge transport interface and an excellent passivation of the silicon dioxide surface. A mobility of up to 0.63 cm\({}^{2}\)/Vs and 0.2 cm\({}^{2}\)/Vs were obtained from the devices based on the PS and PMMA polymeric additive. [PERSON] et al. combined the PS additive (Mw 280k) with a meniscus coating to align TIPS pentacene [116]. Hf/HfO\({}_{2}\) or Ta/Ta\({}_{2}\)O\({}_{5}\) was employed as the gate and gate dielectric layer. Different coating temperature of 30 \({}^{\circ}\)C and 70 \({}^{\circ}\)C was tested along with various sweeping speed. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) analysis indicated a vertical phase segregation between TIPS pentacene and PS, yielding a top TIPS pentacene rich and bottom PS rich structure. The results indicated a maximum average mobility of 0.51 cm\({}^{2}\)/Vs at a sweeping speed of 0.75 mm/s at 70 \({}^{\circ}\)C, and of 0.4 cm\({}^{2}\)/Vs at a sweeping speed of 0.01 mm/s at 30 \({}^{\circ}\)C. The enhancement of charge carrier mobilities at these two particular set of coating temperature and sweeping speed conditions can be attributed to the excellent alignment of TIPS pentacene along a uniform direction according to the polarized microscopic imaging. [PERSON] et al. reported the employment of various polymer dielectric materials tune the charge transport of organic semiconductors from _p_-type to _n_-type performance [117]. These polymers including PS (Mw 280k), PMMA (Mw 120k), poly(4-vinyl phenol) (PVP) (Mw 25k), poly(vinyl alcohol) (PVA) (Mw 130k) and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), were deposited onto the silicon dioxide gate dielectric as an additional dielectric layer. Then by using a droplet-pinned crystallization method, TIPS pentacene crystals were formed based on the nonpolar solvent hexane which prevents adverse effect on electron transport as in the case of polar solvent. Polarized optical imaging indicated that crystals were aligned towards a uniform direction for all types of polymeric dielectric layers, while the PMMA surface yielded a smooth morphology. A maximum hole mobility of 4 cm\({}^{2}\)/Vs and electron mobility of 0.088 cm\({}^{2}\)/Vs was demonstrated from thin film transistors based on the PS polymeric dielectric layer, whereas a hole mobility of 2.5 cm\({}^{2}\)/Vs and a maximum electron mobility of 0.48 cm\({}^{2}\)/Vs was obtained from the counterpart based on the PMMA polymeric dielectric layer. No _n_-type performance was observed from devices with PVP dielectric which was attributed to the hydroxyl groups on the PVP surface as electron trap centers. [PERSON] et al. investigated the amalgamation of PS (Mw 350k) with TIPS pentacene to modulate crystal morphology and refine the charge transport dynamics of the organic semiconductor [118]. Moreover, a dual-solvent protocol was employed to fine-tune the crystallization kinetics. Hansen solubility parameters were employed to identify solvent-compatibility for TIPS pentacene. Notably, anisole was designated as a solvent that is miscible with PS yet exhibits poor solvency for TIPS pentacene, whereas mesitylene was compatible with TIPS pentacene. Without the implementation of the dual-solvent technique, dissolving TIPS pentacene in mesitylene alone led to the growth of diminutive crystals, attributed to the constrained diffusivity of the PS polymer chains in the solvent, thereby impeding the semiconductor's migration during crystal growth. Figure 9a,b presents optical micrographs of thin films fabricated from mesitylene (single solvent) and a mesitylene-anisole (dual solvent) mixture. Correspondingly, Figure 9c,d shows AFM topographical scans from the same regions.