1：Experimental Design and Method Selection:

The study involved the fabrication of OSCs based on a blend of the conjugated donor polymer PBDB-T and ITIC as acceptor. The spin-Hamiltonian parameters of molecular TEs and charge transfer TEs in ITIC were calculated by Density Functional Theory (DFT) modelling. Spin-sensitive photoluminescence and electrical measurements were conducted to probe the population of triplet states.

2：Sample Selection and Data Sources:

Samples were prepared on Herasil ITO-glass substrates. Devices were fabricated in conventional and inverted structures.

3：List of Experimental Equipment and Materials:

ITIC and PBDB-T were purchased from 1-Material, PEDOT:PSS from Heraeus, Al doped ZnO (AZO) nanoparticle solution from Avantama. Equipment included a Keithley 2612B programmable current–voltage source, a Dektak profilometer, a Princeton Instrument Acton Spectra Pro SP2300 spectrometer, and a modified X-Band spectrometer (Bruker E300) for spin-sensitive measurements.

4：Experimental Procedures and Operational Workflow:

The fabrication process involved cleaning ITO-coated glass substrates, coating with PEDOT:PSS or AZO, spin-coating the active layer, and depositing metal contacts. Spin-sensitive measurements were performed under illumination and at low temperatures.

5：Data Analysis Methods:

Data analysis involved the use of Marcus theory for CT energy determination, DFT calculations for spin properties, and analysis of PLDMR and EDMR spectra to identify triplet states.