Solvent-Vapor-Annealing-Induced Interfacial Self-Assembly for Simplified One-Step Spraying Organic Solar Cells

Abstract

An effective self-assembly vertical alignment of interfacial molecules from an active solution plays an important role in controlling the ultrathin thickness of an interfacial layer and reducing the manufacturing costs of organic solar cells (OSCs). Until now, however, due to the complex multistage film-forming process, this facile one-step coating approach does not work for spray-coated OSCs, while other coating techniques such as spin coating, blade coating, or slot-die coating do. In this work, we found that the simplified one-step spraying OSCs can be successfully implemented with the aid of solvent vapor annealing (SVA) for both fullerene- and nonfullerene-based systems, making the one-step spray-coating technique attractive for future manufacturing of photovoltaic modules. The sprayed self-assembly interfacial molecule can be spontaneously delaminated from ternary organic mixtures and vertically deposited underneath the photoactive layer, boosting high charge separation and transport capability comparable to the conventional two-step spraying OSCs. Furthermore, the SVA-assisted one-step spraying process was comprehensively investigated by a series of characterization techniques combining in situ solvent dynamic drying process and X-ray photoelectron spectroscopy, making the causal relationship between spraying process control and device performance more clear. This work shows that the introduction of SVA into one-step spraying can not only maintain high photovoltaic performance but also advance the large-scale OSC industry.

High‐Efficiency Sequential‐Cast Organic Solar Cells Enabled by Dual Solvent‐Controlled Polymer Aggregation

“…[18,19] Additive strategy, thermal annealing, and solvent annealing are common methods to modulate the morphology of BHJ OSCs, but the introduction of the former is often accompanied by a decrease in device stability, and the post-treatment means exacerbate the complexity of production preparation, which is not conducive to the future commercial production. [20][21][22][23][24][25][26] In contrast to BHJ OSCs, the layer-by-layer solution spin-coating method, also known as the two-step method, allows for separate regulation of the donor and acceptor layer to form the desired vertical structure, which facilitates charge transport and collection, does not rely on the ratio of the donor to acceptor, and is less dependent on the use of additives, solvent concentration, etc. [27][28][29] It is a promising production method to prepare high-efficiency devices.…”

Improved Current Density and Fill Factor of Non‐Fullerene Organic Solar Cells Prepared under Solvent Vapor Atmosphere

“…[17,18] SVA is the post-treatment of the active layer film, and it is very sensitive to the treatment time, which increases the complexity of the optimization of OSCs. [19][20][21] Meanwhile, the treatment of the active layer films in containers like Petri dishes is inconvenient for large-scale films prepared with industrialization methods such as roll-to-roll, blade coating et al…”

Achieving High‐Performance Organic Photovoltaics by Morphology Optimization of Active Layers Using Fluorene‐Based Solid Additives

“…[12,13] To elevate the charge transport efficiency, D/A materials with adequate domains and suitable network directions are necessary. During the fabrication of OSC devices, the nanoscale blend domains can be controlled by different methods, such as thermal annealing (TA), [14][15][16] solvent annealing, [17][18][19] solvent additives, [20,21] and solid additives. [22][23][24][25][26][27] So far, the most used optimization process is adding solvent additives cooperating with TA.…”