An ultrathin multilayer film with well-defined structure containing anionic Poly[[4,4-bis(4-sulphobutyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl]-1,4-phenylene sodium sa (PCPDTPhSO₃Na) and cationic poly(diallydimethyl ammonium chloride) (PDDA) was prepared using layer-by-layer assembly technique. The growth of the film was monitored by UV–Vis absorption spectroscopy, showing regularly consecutive adsorption. The ultrafast third-order nonlinear optical (NLO) properties of the multilayer film were investigated via the 4f coherent imaging measurement with phase object with 190 fs laser pulses at both 400 and 532 nm. The results demonstrate that PCPDTPhSO₃Na/PDDA film exhibited excellent self-focusing effect (n₂ ∼2.42 × 10⁻¹⁶ m²/W) and reverse saturable absorption properties (β ∼6.34 × 10⁻¹⁰ m/W) at 400 nm. In contrast, self-focusing effect (n₂ ∼1.81 × 10⁻¹⁶ m²/W) and saturable absorption properties (β ∼−8.02 × 10⁻¹⁰ m/W) are observed when the laser wavelength (532 nm) is near-resonant with the absorption peak (470 nm). Our studies indicate that the PCPDTPhSO₃Na/PDDA film is a promising candidate for applications in NLO devices.

具有明确结构的超薄多层薄膜，其包含阴离子聚[[4,4-双（4-磺丁基）-4H-环戊[2,1-b：3,4-b']二噻吩-2,6-二基]使用分层组装技术制备了-1,4-亚苯基钠sa（PCPDTPhSO ₃ Na）和阳离子聚（二烯丙基二甲基氯化铵）（PDDA）。膜的生长通过紫外-可见吸收光谱法进行监测，显示出规律的连续吸附。通过使用190 fs激光脉冲在400和532 nm处的相位对象进行4f相干成像测量，研究了多层膜的超快三阶非线性光学（NLO）特性。结果表明，PCPDTPhSO ₃的Na / PDDA膜表现出优异的自聚焦效应（Ñ ₂ ~2.42×10 ^-16 米² / W）和反向可饱和吸收特性（β ~6.34×10 ^-10 在400nm米/ W）。与此相反，自聚焦效应（Ñ ₂ ~1.81×10 ^-16 米² / W）和可饱和吸收特性（β〜-8.02×10 ^-10 米/ W），观察到当激光波长（532纳米）是靠近-与吸收峰（470 nm）共振。我们的研究表明，PCPDTPhSO ₃ Na / PDDA膜是在NLO器件中应用的有前途的候选者。