Improved Photovoltaic Properties of Polymer Solar Cells with a Phenyl Compound as an Additive

Abstract

A phenyl compound with electron withdrawing substituents, 3-fluoro-4-cyanophenol (FCP), was used as an additive in polymer solar cells with a P3HT [poly(3-hexyl thiophene)]:PCBM [[6,6]-phenyl-C61-butyric acid methyl ester] blend film. Under simulated solar illumination of AM 1.5 (100 mW/cm2), the devices fabricated using a P3HT:PCBM (1:0.9 w:w) layer blended with 5 wt% of FCP achieved an enhanced power conversion efficiency (PCE) of 4.8% due to the improved short circuit current and fill factor, as compared to reference cells with PCE = 4.1%. UV-visible absorption spectra, X-ray measurements and carrier mobility studies revealed that FCP facilitated the ordering of the P3HT chains, resulting in higher absorbance, larger crystal size, closer packing and enhanced hole mobility.

Effective End Group Modification of Poly(3-hexylthiophene) with Functional Electron-Deficient Moieties for Performance Improvement in Polymer Solar Cell

“…Another notably emerged 2D GIWAXS halo at a q of 1.360 Å –1 ( d = 4.62 Å) in all the blend films is attributed to disordered short-range packing of PCBM, whose diffraction intensities have the same trend as that of the P3HT domains, with the sequence of P3HT-end-OXD > P3HT-end-H/Br ≫ P3HT-end-TAZ. These phenomena of higher crystallinity and closer packing in the P3HT-end-OXD:PCBM blend suggest that OXD end groups with a planar structure can provide similar functionality as nonvolatile additives − in P3HT:PCBM-based PSCs to assist the interchain interaction of P3HT for an improved degree of crystallinity in P3HT domains as achieved in the solvent annealing treatment, resulting in more efficient pathways with a lower resistance for charge carrier transport to the electrodes.…”