This study demonstrates the performance improvement of ultrasonic spray deposited bulk heterojunction type polymer solar cells through droplet boundary reduction assisted by acoustic substrate vibration of varying frequencies between 0–20 kHz. The optimum performance was achieved at 15 kHz of applied frequency, where ∼68% improvement in short-circuit current density and ∼85% improvement in overall cell efficiency were observed compared to the reference devices fabricated on stationary substrates. The performance enhancement is mainly attributed to the improved film morphology due to uniform and homogenous droplet spreading and coalescence under the influence of acoustic vibration. Systematic improvement was observed until 15 kHz when smooth films with significantly reduced droplet boundaries were observed with surface roughness around 10 nm only. However, beyond this point, higher frequencies were found to have detrimental effect on film formation. Significant improvement was observed for every cell parameter for 15 kHz samples. Almost ∼16% enhancement in carrier generation rate and ∼46% enhancement in exciton dissociation probability were observed, as estimated from the photo-current analysis. Urbach energy estimation reveals that the films, prepared at 15 kHz substrate vibration, forms less amount of band edge localized defect states (E_{u (no vibration)} = 161 meV and E_{u (15 kHz)} = 120 meV), resulting into reduced non-radiative recombination and better performances. The presented approach opens up new pathways for uniform and scalable thin film growth through acoustic substrate vibration assisted ultrasonic spray deposition technique, which would be beneficial for large scale industrial organic photovoltaic production.

这项研究表明，通过在0–20 kHz之间变化的频率的声学基板振动辅助液滴的边界减小，可以改善超声喷涂沉积的整体异质结型聚合物太阳能电池的性能。最佳性能是在施加频率为15 kHz时实现的，与在固定基板上制造的参考器件相比，短路电流密度提高了约68％，总电池效率提高了约85％。性能的提高主要归因于在声振动的影响下均匀且均匀的液滴散布和聚结，从而改善了薄膜的形貌。观察到直到15 kHz为止的系统性改善，此时观察到的液滴边界明显减小的平滑膜的表面粗糙度仅为10 nm左右。但是，超过这一点，发现较高的频率对成膜有不利影响。对于15 kHz采样，每个单元参数都得到了显着改善。根据光电流分析估计，观察到载流子生成速率提高了约16％，激子离解概率提高了约46％。Urbach能量估算表明，以15 kHz基底振动制备的薄膜形成较少量的能带边缘局部缺陷态（E_{u （无振动）} = 161 meV，E _{u （15 kHz）} = 120 meV），从而减少了非辐射复合并提高了性能。提出的方法通过声学基底振动辅助超声喷涂沉积技术开辟了均匀且可扩展的薄膜生长的新途径，这将有利于大规模工业有机光伏生产。