Due to computational limitations and the extensive variety of chemical space, our dataset for RESP charge contains conjugated molecules consisting of no more than 200 atoms. We evaluate the transferability of our E3NN model to conjugated polymers, given their significance in the field of OSCs. Three typical conjugated polymers are selected to compare their RESP charges predicted by our E3NN model and reference QM methods. To keep the QM computation affordable, the sizes of three conjugated polymers are limited to around 500 atoms. As shown in Figure , the predictive accuracy of our E3NN for P3CN4HT is lower than that for PV13 and PQTF6, with the R 2 of 0.89 and MAE of 0.044. This diminished accuracy can be ascribed to P3CN4HT's relatively lengthy side chains, which cause stronger