Fig. 2

UV–vis absorption and DSC thermogram of small molecule donors. a Normalized absorption spectra of DR3TBDTC and DR3TBDTT in CB solution (1 × 10⁻⁵ M) and in thin film (spin-coated from CB solution). b DSC second heating and cooling cycles of DR3TBDTC and DR3TBDTT in nitrogen atmosphere with a scan rate of 10 °C min⁻¹