摘要： The hole transport layer (HTL) and back electrode play a significant role in the stability of the flexible organic photovoltaic (OPV) module. In particular, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), a widely used hole transport material, is known to be associated with many degrading factors in the OPV field. This study highlights the impact of the PEDOT:PSS layer on thermal stability using a thermal accelerating test of flexible OPV modules with inverted structures of indium tin oxide/ZnO/photoactive layer/PEDOT:PSS/Ag. The results confirm that thermal degradation of the OPV devices depends on heat temperature, in which the OPV performance degrades by a notable decrease in the open-circuit voltage (Voc) as the temperature increases from 65 °C to 85 °C. Moreover, the stability of the Voc is enhanced when the PEDOT:PSS is thicker and contains polar solvent DMSO as an additive, suggesting that the thermal degradation can correlate with the properties of the PEDOT:PSS layer. In addition, microscope images of the active layers show that the surface damage is attributed to a residual solvent of printed Ag electrode, thereby resulting in a thermally-induced drop in the short circuit current density (Jsc). More detailed descriptions are presented in this paper, and the results are expected to offer comprehensive understanding of the thermal degradation mechanism of OPV module.