Fair and meaningful device performance comparison among luminescent solar concentratorphotovoltaic (LSC-PV) reports cannot be realized without a general consensus on reporting standards in LSC-PV research. Therefore, it is imperative to adopt standardized characterization protocols for these emerging types of PV devices that are consistent with other PV devices. This commentary highlights several common limitations in LSC literature and summarizes the best practices moving forward to harmonize with standard PV reporting, considering the

Practical deployment of TPV technologies requires high power conversion efficiency (PCE) with high aesthetic quality including high average visible transmittance (AVT) and color rendering index (CRI), which can be simultaneously achieved by preferentially harvesting the ultraviolet (UV) and near-infrared (NIR) parts of the solar spectrum. [1,6] Therefore, it is beneficial to simultaneously fine-tune the absorption cutoff edges precisely at the UV/visible (VIS) and VIS/NIR borders to maximize the visible transmission (435-675 nm). [1,3,4] In the past 5 years, efforts have been made to achieve high PCE and visible transparency in TPVs. For example, the bandgaps of organometallic halide perovskite materials were sensitively tuned by compositional engineering for UV-selective-harvesting TPVs; [7,8] a series of novel low-bandgap polymer donors and non-fullerene acceptors have been applied in organic PV devices, [9,10] and excellent photovoltaic performance with distinct NIR selectivity has been demonstrated; [7,9,11-14] tandem architectures have also been utilized in TPVs to selectively harvest both UV and NIR portion of the incident solar spectrum, substantially reducing thermal losses and improving the output photovoltaic performance despite limitations imposed by current-voltage matching; [7,12] the utilization of optical outcoupling layers for VIS photons and various types of transparent electrodes can simultaneously enhance the visible transparency and the utilization of invisible photons. [11] Currently, the PCE of thin-film TPVs have reached ≈8-10%, however, the highest reported AVT is around 40-50% due to considerable parasitic absorption from the electrodes, active layers, and non-ideal wavelength-selectivity. [11,12,15] Alternatively, transparent luminescent solar concentrators (TLSCs) optically shift the solar energy conversion to edgemounted traditional PV cells via waveguided photoluminescence (PL) and total internal reflection. Without the presence of electrodes and device patterning, the structural simplicity substantially improves the defect tolerance and enables TLSCs with distinct wavelength-selectivity to achieve the highest possible visible transparency, circumventing several of the challenges for thin-film TPVs and simplifying the manufacturing. [1,3,5] Much of the previous work on TLSCs with NIR harvesting have absorption profiles that have limited UV capture with PCEs up to around 1% and AVTs above 70% for a light utilization efficiency (LUE, equal to PCE × AVT, which is introduced Visibly transparent luminescent solar concentrators (TLSC) can optimize both power production and visible transparency by selectively harvesting the invisible portion of the solar spectrum. Since the primary applications of TLSCs include building envelopes, greenhouses, automobiles, signage, and mobile electronics, maintaining aesthetics and functionalities is as important as achieving high power conversion efficiencies (PCEs) in practical deployment. In this work, massive-downshifting phosphorescent nanoclusters and ...

Transparent and semitransparent photovoltaics offer an exciting opportunity to integrate existing infrastructure with renewable energy. Organic photovoltaics (OPVs) are key enablers for wavelength‐selective transparent photovoltaics (TPVs) because of their selective absorption in the near‐infrared (NIR) that enables simultaneously high power conversion efficiency (PCE) and average visible transmittance (AVT). The recent rise of OPVs and TPVs has been accelerated in large part by the development of nonfullerene acceptors (NFAs) as highly adaptable deep NIR harvesting materials. Herein, sequential layer‐by‐layer (LBL) deposition of a selectively NIR absorbing nontraditional acceptor polymer is paired with a NIR absorbing donor IEICO‐4F that is typically considered an NFA via solvent orthogonality. With detailed optimization of the active layers and top electrode, semi‐transparent photovoltaics with a PCE of 8.8%, AVT of 40.9%, and a light utilization efficiency of 3.6% are demonstrated. The LBL approach enables explicit optical modeling of the device structure to extract exciton diffusion lengths >100 nm for both the polymer and IEICO‐4F with a transition in charge collection length regimes dependent on the acceptor thickness. Furthermore, the LBL deposition technique enables an investigation of the full range of polymer thickness and its impact on power generation and optical performance.

Two-dimensional (2D) Ruddlesden–Popper (RP) halide perovskite has attracted significant attention as a promising candidate for high-efficiency light sources. RP perovskites, when synthesized into well-defined nanowires (NWs), have the potential to serve as nanoscale coherent light sources by incorporating optical cavity effects with their light emission behaviors. However, RP perovskites tend to grow in macroscopic thin sheets as opposed to relevant NW structures due to the layered nature of the crystal lattice, which necessitates a new way of controlling nanoscale morphologies. Here, we achieve NWs of RP BA2PbBr4 (BA = butylammonium), for the first time, using chemical vapor deposition (CVD) by systematically navigating a wide range of growth conditions and constructing growth regimes of distinct morphologies. Of the two particular regimes that produce well-formed nanostructures, we find that RP BA2PbBr4 grows into energetically favored thin nanoplatelets (NPLs) at high temperatures, whereas intermediate temperatures allow it to first grow into three-dimensional (3D) pyramidal nuclei and then get elongated into NWs upon continued growth. We propose temperature-dependent diffusion of surface species as a deciding factor of our morphological control. We present crystallographic and elemental analyses to confirm that our NWs have the appropriate lattice structures and chemical stoichiometry of BA2PbBr4. Static and time-resolved optical measurements show quantized absorption and emission features at 400 and 406 nm, respectively, with a radiative decay time of 1.7 ns that is much quicker than the 8.7 ns decay time of a prototypical 3D CsPbBr3 perovskite. The RP NWs exhibit a strong exciton binding energy of 279 meV, which can be understood by the reduced dimensionality of BA2PbBr4. The strong absorption and radiative emission characteristics suggest that the RP BA2PbBr4 NWs are good candidates as bright, ultrasmall light sources for nanophotonic and optical communication applications.

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