Alejandro Ortiz

In this work were made the synthesis of symmetric and asymmetric pyridine–diarylamine derivatives through Buchwald–Hartwig cross-coupling reactions using 2,6- and 2,5-dibromopyridine cores functionalized with bis(4-methoxyphenyl)amine (DPA) and iminodibenzyl (IMB) donor units. The influence of molecular symmetry and donor structure on the electronic and optical properties of the resulting compounds was systematically investigated through photophysical, electrochemical, and theoretical studies. UV–Vis spectroscopy revealed absorption bands associated with π–π* transitions and intramolecular charge-transfer (ICT) processes, with the asymmetric 2,5-substituted derivatives exhibiting red-shifted absorption relative to their symmetric 2,6 analogues, indicating enhanced donor–acceptor electronic communication. Fluorescence measurements showed blue emission with quantum yields strongly dependent on both substitution pattern and donor rigidity. Solvatochromic studies confirmed the presence of excited-state charge-transfer processes, while cyclic and square-wave voltammetry demonstrated that asymmetric substitution significantly modifies the frontier molecular orbital energies, leading to improved electron-donating character. Density functional theory (DFT) and time-dependent DFT calculations successfully reproduced the experimental optical behavior and revealed distinct ICT mechanisms depending on the substitution pattern. In the 2,5-substituted derivatives, electron transfer occurs from the diarylamine donor toward the pyridine core, whereas an opposite charge-transfer direction was observed for the 2,6-substituted systems. These findings provide valuable insights into the structure–property relationships governing pyridine–diarylamine conjugated systems and highlight molecular symmetry as a key parameter for tuning their optoelectronic behavior.

In this work were made the synthesis of symmetric and asymmetric pyridine–diarylamine derivatives through Buchwald–Hartwig cross-coupling reactions using 2,6- and 2,5-dibromopyridine cores functionalized with bis(4-methoxyphenyl)amine (DPA) and iminodibenzyl (IMB) donor units. The influence of molecular symmetry and donor structure on the electronic and optical properties of the resulting compounds was systematically investigated through photophysical, electrochemical, and theoretical studies. UV–Vis spectroscopy revealed absorption bands associated with π–π* transitions and intramolecular charge-transfer (ICT) processes, with the asymmetric 2,5-substituted derivatives exhibiting red-shifted absorption relative to their symmetric 2,6 analogues, indicating enhanced donor–acceptor electronic communication. Fluorescence measurements showed blue emission with quantum yields strongly dependent on both substitution pattern and donor rigidity. Solvatochromic studies confirmed the presence of excited-state charge-transfer processes, while cyclic and square-wave voltammetry demonstrated that asymmetric substitution significantly modifies the frontier molecular orbital energies, leading to improved electron-donating character. Density functional theory (DFT) and time-dependent DFT calculations successfully reproduced the experimental optical behavior and revealed distinct ICT mechanisms depending on the substitution pattern. In the 2,5-substituted derivatives, electron transfer occurs from the diarylamine donor toward the pyridine core, whereas an opposite charge-transfer direction was observed for the 2,6-substituted systems. These findings provide valuable insights into the structure–property relationships governing pyridine–diarylamine conjugated systems and highlight molecular symmetry as a key parameter for tuning their optoelectronic behavior.

Inert gamma degradation of 46 organic hole transport materials reveal a high average ionizing dose tolerance of more than 10 kGy, with BODIPY molecules exceeding 100 kGy.

Perovskite solar cells (PSCs) have recently achieved over 26 % power conversion efficiency, challenging the dominance of silicon‐based alternatives. This progress is significantly driven by innovations in hole transport materials (HTMs), which notably influence the efficiency and stability of PSCs. However, conventional organic HTMs like Spiro‐OMeTAD and PTAA, although highly efficient, suffer from thermal degradation, moisture ingress, and high cost. This study explores the potential of iminodibenzyl, a moiety known for its strong electron‐donating capabilities in pharmaceutical applications, as a novel HTM. A series of fluorene‐based derivatives incorporating iminodibenzyl (TMF‐2 and TDF‐2) and diphenylamine (TMF‐1 and TDF‐1) units were synthesized and characterized. The new HTMs demonstrated commendable optical, electrochemical, and thermal properties, as well as enhanced photostability. Among them, TDF‐2 achieved a power conversion efficiency (PCE) of 19.38 %, the highest of the new materials. Although these efficiencies are slightly lower than the benchmark PTAA (20.20 %), the study underscores the potential of iminodibenzyl to enhance photostability and increase HOMO levels, making it a promising candidate for future HTM development in PSCs.

Perovskite solar cells (PSCs) have become a research hotspot since their dramatic increase in power conversion efficiency (PCE), surpassing 26% due to advances in cell engineering and interfacial layers. Within the last factor, hole transporting materials play a crucial role in enhancing device performance and stability. Among several molecular building blocks, BODIPYs are attractive for the design of novel hole transporting material (HTMs) due to their outstanding photophysical and charge transport properties easily tuned by synthetic modifications. Herein, the synthesis of five new BODIPY‐based HTMs PyBDP 1–5 are reported, functionalized at the meso‐ and α‐ positions with pyrenyl and arylamino units, respectively. The resulting compounds exhibit broad absorption in the visible region, remarkable thermal stability, narrow bandgaps, suitable energy levels, and good hole extraction capability, as subtracted from experimental and computational characterizations. The performance of the BODIPY derivatives as HTMs is evaluated in planar inverted (p‐ i ‐n) PSCs and compared to commonly used PTAA, resulting in highly efficient systems, reaching PCEs very close to that obtained with the reference polymer (21.51%). The incorporation of these BODIPY‐based HTMs result in an outstanding PCE of 20.37% for devices including PyBDP‐1 and 19.97% for devises containing PyBDP‐3 , thus demonstrating that BODIPY derivatives are a promising alternative to obtain simple and efficient organic HTMs.

The morphology of the active layer in organic solar cells is fundamental for achieving high power conversion efficiency. However, the morphological characteristics for optimal performance are still being investigated. An atomistic computational approach is required to determine the relationship between active layer morphology and performance. Since the organic solar cell has multiple phases and interfaces, the computational modeling of charge generation and transport is challenging. We then used a set of push–pull semiconductors to illustrate how the electronic transmission spectrum, derived from the Landauer–Büttiker formalism, can be used to investigate the efficiency of coherent charge transport across anisotropic organic solids. The electronic transmission spectrum was calculated from the electronic band structure obtained using the density-functional-based tight-binding method. We found that coherent charge transport was more efficient along the direction parallel with the interface between the electron-acceptor and electron-donor moieties for a herringbone morphology.

A tailored design of asymmetric hole-transporting materials (HTMs) is reported with the synthesis of a family of new HTMs based on the use of the 5 H -dithieno[3,2- b :2′,3′- d ]pyran (DTP) moiety endowed with donor p -methoxytriphenylamines.

Solar cells based on organic compounds are a proven emergent alternative to conventional electrical energy generation. Here, we provide a computational study of power conversion efficiency optimization of boron dipyrromethene (BODIPY) derivatives by means of their associated open-circuit voltage, short-circuit density, and fill factor. In doing so, we compute for the derivatives’ geometrical structures, energy levels of frontier molecular orbitals, absorption spectra, light collection efficiencies, and exciton binding energies via density functional theory (DFT) and time-dependent (TD)-DFT calculations. We fully characterize four D−π–A (BODIPY) molecular systems of high efficiency and improved J_sc that are well suited for integration into bulk heterojunction (BHJ) organic solar cells as electron-donor materials in the active layer. Our results are twofold: we found that molecular complexes with a structural isoxazoline ring exhibit a higher power conversion efficiency (PCE), a useful result for improving the BHJ current, and, on the other hand, by considering the molecular systems as electron-acceptor materials, with P3HT as the electron donor in the active layer, we found a high PCE compound favorability with a pyrrolidine ring in its structure, in contrast to the molecular systems built with an isoxazoline ring. The theoretical characterization of the electronic properties of the BODIPY derivatives provided here, computed with a combination of ab initio methods and quantum models, can be readily applied to other sets of molecular complexes to hierarchize optimal power conversion efficiency.