One possibility of molecular packing change during II-III transition is shown in Figure , where molecules form dimers with the nearest neighbor in the original polymorph II structure. Since the crystal packs in these 1-D π-stacks with dimer-like pairs already, this would be a natural progression. While the dimer formation may be plausible, we cannot say with certainty how those dimers then pack to form polymorph III. Regardless of the new core packing motif, to facilitate the II-III also necessitates alkyl chain melting, indicated by increased gauche conformers. Moreover, this side chain melting is consistent with the kinetic trapping observed (Figure and Movie S4). As we observe upon cooling to 37 °C, the alkyl chains return to a frozen state however there appears to be residual biradicals not yet quenched by cooling, owing to a residual lifetime of the biradical state (Figure ). As a result, polymorph III is trapped and would not return to polymorph I due to freezing the alkyl chains before the conjugated cores rearrange back into polymorph I that may require quenching of biradical species. However, without the full structure of polymorph III, we are left only to postulate possible molecular packings. Nevertheless, we can suggest the nucleation and growth polymorph transition is the result of increased core-core interactions triggered by the biradical formation, and the large packing changes are necessarily facilitated by increased molecular mobility from the melted alkyl side chains. Electronic and device properties. We worked to demonstrate the control and design of organic electronics utilizing these transition mechanisms. We fabricated single crystal devices to measure the twopoint-probe conductivity of each polymorph (Figure ). The crystals were pre-bent fixed at two ends by PEDOT:PSS electrodes. When heated to trigger I-II transition, the crystal would straighten from the prebent state due to shape change shown in Figure . We observed a 6-fold decrease in conductivity at the I-II transition, with good recoverability during cooling albeit with a hysteresis. Moreover, we see a moderate increase in conductivity upon polymorph II-III transition. We suspect this recovery of conductivity may be a result of charge carrier doping through the presence of biradicals, similar to Wudl et. al., which showed a self-doping effect . This self-doping process may compete with the reduction in charge transfer pathways due to structural transitions.