Morphology Inversion of a Non‐Fullerene Acceptor Via Adhesion Controlled Decal‐Coating for Efficient Conversion and Detection in Organic Electronics

Abstract

In this study, a promising film formation technique is highlighted, named mold-assisted decal-coating, as a thin film transfer printing process using the polyurethane acrylate-based stamping mold. By optimizing the surface energy of the mold with wetting coefficient theory, the mold-assisted decal-coating process is successfully demonstrated by transferring the photoactive layer composed of the polymer donor, poly[4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] and a narrow bandgap non-fullerene acceptor (NFA), 2,2′-[[4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydros-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl]bis[[4-[(2-ethylhexyl)oxy]-5,2thiophenediyl]methylidyne(5,6-difluoro-3-oxo-1H-indene-2,1(3H)-diylidene)]] bis[propanedinitrile]. This process induces a well-ordered morphology of photoactive material, prevents damage to the underlying layer by suppressing the solvent penetration. Both photovoltaic cells and photodetectors prepared by the decal-coated photoactive layers containing fluorinated NFAs showed higher performance (power conversion efficiency = 10.69% and specific detectivity = 1.27 × 10 12 A cm Hz 1/2 W −1 , respectively) than those of cells prepared by the spin-coating method owing to morphology inversion and smoother interface that led to suppressed internal resistance and enhanced charge flow in normal structure. Thus, the reproducible decal-coating process using a customized elastomeric mediator is an important thin film coating technique for efficient next-generation organic optoelectronic materials.

Preferred Acceptor-Domain Positioning via a Phase-Switched Bulk Heterojunction for Self-Powered Photodetector and Photovoltaic Applications

“…Subsequently, the applied wetting coefficient (ω wc ) based on the interfacial energy value between materials predicts a thermodynamically stable wetting preference, confirming the possibility of successful phase switching BHJ formation . The wetting coefficient is defined as …”

“…Subsequently, the applied wetting coefficient (ω wc ) based on the interfacial energy value between materials predicts a thermodynamically stable wetting preference, confirming the possibility of successful phase switching BHJ formation . The wetting coefficient is defined as ω normalw normalc = γ normalm normalo normall normald − normalB normalH normalJ − γ normalB normalH normalJ − normalP normalE normalD normalO normalT : normalP normalS normalS γ normalm normalo normall normald − normalP normalE normalD normalO normalT : normalP normalS normalS …”

Organic photodiodes: device engineering and applications

“…In the structure, pure donor/ accepter phases were formed in the regions near the anode/ cathode, respectively, to effectively suppress undesired charge injection, while the center region having mixed donor/acceptor interfaces for substantial photocurrent generation. To obtain such a q-PHJ, sequential deposition of the small molecule acceptor and the polymer donor and morphology engineering were developed [89][90][91][92][93]. Wei et al recently fabricated a self-powered NIR OPD using the sequential deposition method [94].…”

Morphology Evolution via a Generic Solvent Additive Concept Enables Large‐Area All‐Polymer Solar Cells with Negligible PCE Loss

“…[45] Since the OSC can be equivalent to a constant current source in the working state, the reduced output current can well explain why the FF of the large-area device is smaller than that of the small-area device. [46,47] Under the same device area, the internal resistance of the PTzBI:N2200 (0.5% DIO) device is larger than that of the PTzBI:N2200 (0% DIO) device, indicating that the addition of DIO helps to suppress the carrier recombination and thus boost the J SC and FF of large-area PTzBI:N2200 device.…”