Hierarchical phase separation in all small-molecule organic solar cells

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 24; no. 11
• Main Authors: Iqbal, Muhammad Junaid, Zhang, Jianqi, Wei, Zhixiang
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-11-2022; Springer Nature B.V
• Subjects: Acceptor materials; Characterization and Evaluation of Materials; Charge transport; Chemistry and Materials Science; Circuits; Computer architecture; Cytology; Diffusion layers; Diffusion length; Energy conversion efficiency; Fabrication; Inorganic Chemistry; Lasers; Materials Science; Morphology; Nanotechnology; Open circuit voltage; Optical Devices; Optics; Optimization; Phase separation; Photonics; Photovoltaic cells; Physical Chemistry; Review; Self-assembled Functional Nanomaterials and Devices in Asia; Short circuit currents; Short-circuit current; Solar cells; Vertical separation; Small molecular donor; Small molecular acceptor; Multi-length scale phase separation; Hierarchical morphology; Organic solar cells; Bimodal domain size distribution
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-022-05568-3

Solution processable small-molecule organic solar cells have progressed a lot in terms of donor and acceptor materials, device architectures, fabrication techniques, and optimization methodologies which have enabled credible performance gains. The hierarchical active layer morphology is one such strategy that has led to significant performance gains by overcoming the earlier systems’ shortcomings and providing an optimized active layer morphology with features well within the confines of the excitonic diffusion length (
L
D
) (5–30 nm). Multi-length scale domains, lateral and vertical phase separation, and interconnected network-like charge transport pathways are some of the key morphological features that lead to enhanced open-circuit voltage, short circuit current, fill factor, and in turn, greater power conversion efficiencies. This has furthered our understanding of the relationship between morphology and the charge generation, transport, disassociation, and extraction processes. In this review, we summarize the efforts concentrated on achieving such optimized hierarchical morphologies in binary and ternary small molecule-based organic solar cells and provide insights into the relationship between performance and morphology.