## 4 Conclusions  
In summary, a novel donor-acceptor copolymer **P(F)DPP-TP)** consisting of thieno[3,2-\(b\)]pyrrole and diketopyrrolopyrrole with furan spacer units was synthesized. The **P(F)DPP-TP)** polymer showed better planarity with the furan spacer, as suggested by the DFT calculations. The UV-Vis data indicate that there might be possible \(\pi\)-stacking and lamellar packing in the solid-state polymer. The highest hole mobility of 0.42 cm\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\) measured in the BGBC device annealed at 200 \({}^{\circ}\)C for **P(F)DPP-TP)** was four times higher than that of **P(DPP-TP)**[26]. Moreover, the on/off ratio was \(10^{2}\) times larger than that of **P(DPP-TP)**. Furthermore, the GIXRD and AFM data confirmed that thermal annealing increased the polymer's crystallinity and fibrillar arrangement in thin films to facilitate the improvement of charge carrier mobilities. Additionally, it is noteworthy that employing furan as a spacer unit in TP- and DPP-based donor-acceptor-type polymers could enhance OFET performances compared to thiophene spacer.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12063150/s1](https://www.mdpi.com/article/10.3390/app12063150/s1)]([https://www.mdpi.com/article/10.3390/app12063150/s1](https://www.mdpi.com/article/10.3390/app12063150/s1)), Detailed experimental methods, detailed synthesis methods of materials, NMR spectra, DFT calculations, OFET transfer and output curves, and DSC and TGA spectra of **P(F)DPP-TP)** are included in the Supplementary Materials. Scheme S1: Synthesis of the poly(((methylthioopyrrolo)furanyl)diketopyrrolopyrrol) **P(F)DPP-TP)**[26, 47]. Figure S1: 1 HNMR spectrum of 2.5-bis(2-decyltetrad)-3,6-di(furan-2-yl)-2,5-dihydroxyproylro(3,4-clyyrrole-1,4-dione. Figure S2: 13 CNMR spectrum of 2.5-bis(2-decyltetrad))-3,6-di(furan-2-yl)-2,5-dihydropyproylo[3,4-]pyrorole-1,4-dione. Figure S3: 1 HNMR spectrum of 3,6-bis(5-bromofuran-2-yl)-2,5-bis(2-decyltetrad)-2,5-dihydropyrypo[3,4-]cyprrole-1,4-dione. Figure S4: 13 CNMR spectrum of 3,6-bis(5-bromofuran-2-yl)-2,5-bis(2-decyltetrad)-2,5-dihydropyrypo[3,4-]cyprrole-1,4-dione. Figure S5: 1 HNMR spectrum of **P(FDPP-TP)** polymer. Figure S6: DFT calculation data of Spartan 16 software (B3 LYP/6-31G*). Figure S7: OFET transfer curves (a-d) and output curves (e-h) of bottom-gate top-contact devices: (a,e) RT, (b,f) 100 \({}^{\circ}\)C, (c,g) 150 \({}^{\circ}\)C, and (d,h) 200 \({}^{\circ}\)C. Figure S8: OFET transfer curves (a,b) and output curves (c,d) at 225 \({}^{\circ}\)C of (a,c) BGBC and (b,d) BGTC. Figure S9: (a) DSC thermogram and (b) TGA thermogram of **P(FDPP-TP)**. Figure S10: GIXRD pattern of **P(FDPP-TP)** thin films on SiO\({}_{2}\) substrates at different temperatures. The crystallite sizes considering (100) peak from XRD patterns were calculated by using Scherrer formula as 7.44 nm, 7.53 nm, 8.91 nm, and 9.23 nm for samples not annealed, annealed at 100 \({}^{\circ}\)C, annealed at 150 \({}^{\circ}\)C, and annealed at 200 \({}^{\circ}\)C, respectively [47]. Table S1: Optoelectronic properties of **P(FDPP-TP)**. Table S2: BGBC OFET data of **P(FDPP-TP)**. Table S3: OFET data of BGTC devices of **P(FDPP-TP)**.  
**Author Contributions:** Synthesis, P.L.G., C.M.U.G., R.G. and C.B.; OFET measurements, P.L.G., C.M.U.G. and Z.M.; Data analysis, preparation of manuscript, P.L.G., C.M.U.G., R.G., C.B., Z.M., A.S., M.C.B. and M.C.S. All authors have read and agreed to the published version of the manuscript.  
**Funding:** Welch Foundation (Grant AT-1740); National Science Foundation (CHE-1609880 and CHE-1566059).  
**Acknowledgments:** We want to acknowledge the Welch Foundation (Grant AT-1740) and the National Science Foundation (CHE-1609880 and CHE-1566059) for financial support. M.C.S. also acknowledges the Eugene McDermott Foundation for the generous endowed chair support.  
**Conflicts of Interest:** The authors declare no conflict of interest.