Molecular design of near-IR dyes with different surface energy for selective loading to the heterojunction in blend films

A new quantum-safe multivariate polynomial public key digital signature algorithm

We propose a new quantum-safe digital signature algorithm called Multivariate Polynomial Public Key Digital Signature (MPPK/DS). The core of the algorithm is based on the modular arithmetic property that for a given element g, greater than equal to two, in a prime Galois field GF(p) and two multivariate polynomials P and Q, if P is equal to Q modulo p-1, then g to the power of P is equal to g to the power of Q modulo p. MPPK/DS is designed to withstand the key-only, chosen-message, and known-message attacks. Most importantly, making secret the element g disfavors quantum computers' capability to solve the discrete logarithm problem. The security of the MPPK/DS algorithm stems from choosing a prime p associated with the field GF(p), such that p is a sum of a product of an odd prime number q multiplied with a power x of two and one. Given such a choice of a prime, choosing even coefficients of the publicly available polynomials makes it hard to find any private information modulo p-1. Moreover, it makes it exponentially hard to lift the solutions found modulo q to the ring of integers modulo p-1 by properly arranging x and q. However, finding private information modulo the components q and power x of two is an NP-hard problem since it involves solving multivariate equations over the chosen finite field. The time complexity of searching a private key from a public key or signatures is exponential over GF(p). The time complexity of perpetrating a spoofing attack is also exponential for a field GF(p). MPPK/DS can achieve all three NIST security levels with optimized choices of multivariate polynomials and the generalized safe prime p.

Design of ternary additive for organic photovoltaics: a cautionary tale

Silicon phthalocyanines as ternary additives are a promising way to increase the performance of organic photovoltaics. The miscibility of the additive and the donor polymer plays a significant role in the enhancement of the device performance, therefore, ternary additives can be designed to better interact with the conjugated polymer. We synthesized N-9′-heptadecanyl-2,7-carbazole functionalized SiPc ((CBzPho)₂-SiPc), a ternary additive with increased miscibility in poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT). The resulting additive was included into PCDTBT and [6,6]-phenyl C₇₁ butyric acid methyl ester as bulk (PC₇₁BM) heterojunction OPV devices as a ternary additive. While the (CBzPho)₂-SiPc demonstrated strong EQE >30% contribution in the range of 650–730 nm, the overall performance was reduced because (CBzPho)₂-SiPc acted as a hole trap due to its high-lying HOMO energy level. This study demonstrates the importance of the solubility, miscibility, and energy level engineering of the ternary additive when designing organic photovoltaic devices.

Silicon phthalocyanines with carbazole axial functional groups were synthesized to improve the miscibility in PCDTBT and for use as ternary additives in organic photovoltaics.

Horizontal-, Vertical-, and Cross-Conjugated Small Molecules: Conjugated Pathway-Performance Correlations along Operation Mechanisms in Ternary Non-Fullerene Organic Solar Cells

A family of the SM-axis series based on benzo[1,​2-​b:4,​5-​b']​dithiophene and 3-ethylrhodanine (RD) units with structurally different π-conjugation systems are synthesized as a means to understand the structure-property relationship of conjugated pathways in ternary non-fullerene organic solar cells (NF-OSCs) as a third component. The optical and electrochemical properties of the SM-axis are highly sensitive both to the functionalized direction and to the number of RD groups. Enhanced power conversion efficiencies (PCEs) of over 11% in ternary devices are obtained by incorporating optimal SM-X and SM-Y contents from PBDB-T:ITIC binary NF-OSCs, while a slightly lower PCE is observed with the addition of SM-XY. The results of in-depth studies using various characterization techniques demonstrate that working mechanisms of SM-axis-based ternary NF-OSCs are distinctly different from one another: an energy-transfer mechanism with an alloy-like model for SM-X, a charge transfer with the same model for SM-Y, and an energy transfer without such a structure for SM-XY. As extension of the scope, a SM-X-based ternary NF-OSC in the PM6:IT4F system also shows a greatly enhanced PCE of over 13%. The findings provide insights into the effects of conjugated pathways of organic semiconductors on mechanisms of ternary NF-OSCs, advancing the understanding for synthetic chemists, materials engineers, and device physicists.

Universal Nanoparticle Wetting Agent for Upscaling Perovskite Solar Cells

Solution-processed perovskite solar cells reach efficiencies over 23% on lab-scale. However, a reproducible transfer of these established processes to upscaling techniques or different substrate surfaces requires a highly controllable perovskite film formation. Especially, hydrophobic surfaces cause severe dewetting issues. Such surfaces are particularly crucial for the so-called standard n-i-p cell architecture when fullerene-based electron transport layers are employed underneath perovskite absorber films. In this work, a unique and universally applicable method was developed based on the deposition of size-controlled Al₂O₃ or SiO₂ nanoparticles. By enhancing the surface energy, they act as a universal wetting agent. This allows perovskite precursor solutions to be spread perfectly over various substrates including problematic hydrophobic Si-wafers or fullerene self-assembled monolayers (C₆₀-SAMs). Moreover, the results show that the perovskite morphology, solar cell performance, and reproducibility benefit from the presence of the nanoparticles at the interface. When applied to 144 cm² C₆₀-SAM-coated substrates, homogenous coverage can be realized via spin coating resulting in average efficiencies of 16% (maximum 18%) on individualized cells with 0.1 cm² active area. Modules in the same setup reached maximum efficiencies of 11 and 7% on 2.8 and 23.65 cm² aperture areas, respectively.

Influence of Surface Energy on Organic Alloy Formation in Ternary Blend Solar Cells Based on Two Donor Polymers

The compositional dependence of the open-circuit voltage (V_oc) in ternary blend bulk heterojunction (BHJ) solar cells is correlated with the miscibility of polymers, which may be influenced by a number of attributes, including crystallinity, the random copolymer effect, or surface energy. Four ternary blend systems featuring poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) (P3HT₇₅-co-EHT₂₅), poly(3-hexylthiophene-co-(hexyl-3-carboxylate)), herein referred to as poly(3-hexylthiophene-co-3-hexylesterthiophene) (P3HT₅₀-co-3HET₅₀), poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP-10%), and an analog of P3HTT-DPP-10% with 40% of 3-hexylthiophene exchanged for 2-(2-methoxyethoxy)ethylthiophen-2-yl (3MEO-T) (featuring an electronically decoupled oligoether side-chain), referred to as P3HTTDPP-MEO40%, are explored in this work. All four polymers are semicrystalline and rich in rr-P3HT content and perform well in binary devices with PC₆₁BM. Except for P3HTTDPP-MEO40%, all polymers exhibit similar surface energies (∼21-22 mN/m). P3HTTDPP-MEO40% exhibits an elevated surface energy of around 26 mN/m. As a result, despite the similar optoelectronic properties and binary solar cell performance of P3HTTDPP-MEO40% compared to P3HTT-DPP-10%, the former exhibits a pinned V_oc in two different sets of ternary blend devices. This is a stark contrast to previous rr-P3HT-based systems and demonstrates that surface energy, and its influence on miscibility, plays a critical role in the formation of organic alloys and can supersede the influence of crystallinity, the random copolymer effect, similar backbone structures, and HOMO/LUMO considerations. Therefore, we confirm surface energy compatibility as a figure-of-merit for predicting the compositional dependence of the V_oc in ternary blend solar cells and highlight the importance of polymer miscibility in organic alloy formation.

Interface engineering for ternary blend polymer solar cells with a heterostructured near-IR dye

Ternary-blend polymer solar cells can be effectively improved by incorporating a heterostructured near-IR dye, which has a hexyl group compatible with the polymer and a benzyl group compatible with the fullerene. Because of the compatibility with both materials, the heterostructured dye can be loaded up to 15 wt% and hence can boost the photocurrent generation by 30%.

Highly efficient exciton harvesting and charge transport in ternary blend solar cells based on wide- and low-bandgap polymers

Ternary blend solar cells using a crystalline wide-bandgap P3HT and a low-bandgap PSBTBT exhibit good exciton harvesting and charge transport.