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In this work, spatially resolved characterization methods are used to identify loss mechanisms for common $p$-type silicon solar cell architectures, including multicrystalline aluminum back surface field (Al-BSF), monocrystalline Al-BSF, monocrystalline passivated emitter and rear cells (PERC), and bifacial monocrystalline PERC. The characterization methods used in this work include suns-$V_{\mathrm{\text{OC}}}$, photoluminescence imaging, and spatially resolved external quantum efficiency and reflectance measurements. The optical and recombination losses are driven by the material properties, cell processing conditions, and device architecture. These losses are quantified and categorized in terms of underlying mechanisms (e.g., front reflectance, escape reflectance, front recombination, and parasitic optical absorption and recombination in the bulk and rear). The ability to create images of these loss parameters can be used to gain more insight into the materials and manufacturing processes used to produce solar cells, and examples are given in this work to illustrate how these images can help reveal the origin of defects.

Novel electron-deficient low-symmetry perhalogenated azaanalogues of subphthalocyanine, [Cl₂F₈N₂subPc] and [Cl₄F₄N₄subPc], were prepared by mixed co-cyclotrimerization of tetrafluorophthalonitrile and 5,6-dichloropyrazine-3,4-dicarbonitrile in p-xylene in the presence of BCl₃. They were characterized by MALDI mass-spectrometry, UV-VIS, IR, ${}^{13}$C, and ${}^{19}$F NMR spectroscopy, and the molecular structure of [Cl₂F₈N₂subPc] was established by single crystal X-ray diffraction. The spectral-luminescence and redox properties of [Cl₂F₈N₂subPc] and [Cl₄F₄N₄subPc] as well as peculiarities of their electronic structure are compared with the corresponding symmetrically substituted compounds - perfluorosubphthalocyanine, [F${}_{12}$subPc], and hexachlorotripyrazinosubporphyrazine, [Cl₆N₆subPc]. Consecutive substitution of one and two tetrafluorobenzene fragments by dichloropyrazine units leads to stabilization of the frontier $\pi$-molecular orbitals and widening of the HOMO–LUMO gap. As a result, electron-affinity of the macrocycle is increased and the first reduction potentials are increasingly shifted in the less negative region from -0.43 V for [F${}_{12}$subPc] to -0.31 V for [Cl₂F₈N₂subPc], -0.19 V for [Cl₄F₄N₄subPc], and the maxima of the Q-band is shifted hypsochromically from 573 nm to 565 and 553 nm, respectively. Preliminary photoelectrical measurements indicate that novel compounds can be used as acceptor materials in non-fullerene photovoltaic cells.

Imide-based Subphthalocyanines (SubPcs) is gaining momentum as non-fullerene acceptors in organic solar cells (OSCs). Herein we report the synthesis, characterization, and photovoltaic performance of Perylenemonoimide (PMI)-SubPc conjugates in which the PMI is linked to the SubPc core by either alkynes or direct C-C bond. These derivatives are prepared via palladium-catalyzed cross-coupling reactions. The introduction of PMI units results in a red-shifted absorption, which can be described as the combination of the absorption properties of both SubPc and PMIs fragments. The absorption spectra are thus mainly composed of two transitions, one derived from the SubPc Q-band and the other from transitions within the PMI moieties. These PMI-SubPc systems exhibit moderate acceptor properties and therefore their use as non-fullerene acceptors in bulk-heterojunction organic solar cells is briefly explored.