In this study, an alcohol soluble novel naphthalene diimide (NDI)−thiophene-based cathode interface layer (CIL), PNDIT10N, is reported. PNDIT10N was synthesized in a facile three-step method, processed from environmentally friendly benzyl alcohol (BnOH) and employed in inverted polymer solar cells (PSCs). The three polymer donors TQ1, PTNT, and PTB7-Th were paired with the fullerene acceptor PC 71 BM for bulk heterojunction (BHJ) layers to evaluate the CIL. The modification of the indium tin oxide (ITO) electrode with a ∼3 nm thin layer of PNDIT10N yielded a significant reduction of 0.8 eV in the work function, reducing it from 4.6 to 3.8 eV, effectively transforming ITO to a functioning cathode. PSCs with a TQ1/PC 71 BM BHJ layer and incorporating a PNDIT10N interlayer were found to have a high J sc value of 10.5 mA cm −2 , V oc value of 909 mV, and an FF value of 68%, resulting in the highest PCE of 6.7% for TQ1 donor in the inverted device structure. Of note, the interface layer showed a good stability in ambient atmosphere for a 10 d indoor aging period, both in darkness and exposed to direct sunlight. Additionally, flexible PSCs incorporating slot-die coated PNDIT10N, processed from a BnOH− acetone solution, and BHJ layer in air achieved a PCE of 1.6%.

We investigated the effect of adding p-anisaldehyde (AA) solvent to the ink containing poly[[2,60-4,8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7-Th) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:20,30-d0]-s-indaceno[1,2-b:5,6-b0]-dithiophene(ITIC) on the morphology of the active layer. The present study focuses on determining the effect of the additive on the compositions at the surface of the PTB7-Th: ITIC composite and its morphology, forming one side of the interface of the blend with the MoOX electrode, and the influence of the structural change on the performance of devices. Studies of device performance show that the addition of the additive AA leads to an improvement in device performance. Upon the addition of AA, the concentration of PTB7-Th at the surface of the bulk heterojunction (BHJ) increases, causing an increase in surface roughness of the surface of the BHJ. This finding contributes to an understanding of the interaction between the donor material and high work function electrode/interface material. The implications for the interface are discussed.

For organic photovoltaics (OPVs) to be considered commercially viable, the devices should not only achieve high performances, but also have relatively long lifespans. In fact, a major source of lifespan...