Multi-stimuli-responsive fluorescent molecule tetraphenylethylene (TPE) derivative 1 is synthesized, which contains a TPE skeleton and peripheries of two methoxyl groups and one carboxyl group. It shows a typical aggregationinduced emission behavior and also exhibits fluorescence responses to pH change and amine vapors, and multicolored mechanochromic properties. The emission of 1 can be reversibly switched among blue (1p-f, 462 nm, Φ f = 7.4%), bright cyan (1p-h, 482 nm, Φ f = 82.3%), and yellow (1p-g, 496 nm, Φ f = 10.5%) with high contrast through solvent fuming, heating, or grinding. Molecule 1 occurs in four crystalline states (1c-a, 1c-b, 1c-c, and 1c-d) after crystallization from different solvents. The multicolored mechanochromic property is related to the different interactions and packing modes of molecules in the crystals. The crystals with weak fluorescent emission have characteristic porous structures and corresponding intensive XRD diffraction peaks, which are absent in the crystal with intensive fluorescent emission. The porous structures are critical for the fluorescence intensity of the molecules. Upon heating, the porous structures of crystals are damaged and fluorescence is significantly enhanced.

Side chain engineering of conjugated donor–acceptor polymers is a new way to manipulate their optoelectronic properties. Two new diketopyrrolopyrrole (DPP)‐terthiophene‐based conjugated polymers PDPP3T‐1 and PDPP3T‐2, with both hydrophilic triethylene glycol (TEG) and hydrophobic alkyl chains, are reported. It is demonstrated that the incorporation of TEG chains has a significant effect on the interchain packing and thin‐film morphology with noticeable effect on charge transport. Polymer chains of PDPP3T‐1 in which TEG chains are uniformly distributed can self‐assemble spontaneously into a more ordered thin film. As a result, the thin film of PDPP3T‐1 exhibits high saturated hole mobility up to 2.6 cm2 V−1 s−1 without any post‐treatment. This is superior to those of PDPP3T with just alkyl chains and PDPP3T‐2. Moreover, the respective field effect transistors made of PDPP3T‐1 can be utilized for sensing ethanol vapor with high sensitivity (down to 100 ppb) and good selectivity.