In recent years, hybrid perovskite solar cells (HPSCs) have received considerable research attention due to their impressive photovoltaic performance and low-temperature solution processing capability. However, there remain challenges related to defect passivation and enhancing the charge carrier dynamics of the perovskites, to further increase the power conversion efficiency of HPSCs. In this work, the use of a novel material, phenylhydrazinium iodide (PHAI), as an additive in MAPbI 3 perovskite for defect minimization and enhancement of the charge carrier dynamics of inverted HPSCs is reported. Incorporation of the PHAI in perovskite precursor solution facilitates controlled crystallization, higher carrier lifetime, as well as less recombination. In addition, PHAI additive treated HPSCs exhibit lower density of filled trap states (10 10 cm −2 ) in perovskite grain boundaries, higher charge carrier mobility (≈11 × 10 −4 cm 2 V −1 s), and enhanced power conversion efficiency (≈18%) that corresponds to a ≈20% improvement in comparison to the pristine devices.

Achieving long-term stability along with high power conversion efficiency (PCE) is the biggest obstacle for the pursuit of organic−inorganic perovskite solar cells (PSCs) toward commercialization. Herein, we demonstrate additive assisted perovskite crystal growth as an effective strategy to improve both power conversion efficiency and thermal stability of methylammonium lead triiodide (MAPbI 3 ) perovskite solar cells. For this, oxalic acid (OA) with two bifacial carboxylic acid groups was employed as an additive into the perovskite precursor solution, which facilitated modulating the crystallization process leading to increase in grain size, reduced grain boundaries and trap states. Subsequently, devices fabricated with the OA additive showed a power conversion efficiency of 17.12%, compared to the control device with 14.06%. Furthermore, enhanced thermal stability was achieved for the OA-modified PSCs compared to that of the pristine device. The device without the OA additive retained 14% of the initial PCE after only 9 h of heat treatment at 100 °C, whereas for the same condition, the OA-modified device retained 90% after 9 h and even 70% after 19 h. These observations suggest that OA-assisted morphological improvement of perovskite can offer an efficient approach to further improve the performance as well as stability of the PSCs.

Lead (Pb)–Tin (Sn) mixed perovskites suffer from large open-circuit voltage (V oc) loss due to the rapid crystallization of perovskite films, creating Sn and Pb vacancies. Such vacancies act as defect sites expediting charge carrier recombination, thus hampering the charge carrier dynamics and optoelectronic properties of the perovskite film. Here, we report the passivation of these defects using a controlled amount of 2-phenylethylazanium iodide (PEAI) in perovskite precursor solution as a dopant to enhance the performance of the 1.25 eV Pb–Sn low-bandgap perovskite solar cell. It was found that the incorporation of PEAI in the perovskite precursor not only improves the perovskite film quality and crystallinity but also lowers the electronic disorder, thereby enhancing the open-circuit voltage up to 0.85 V, corresponding to V oc loss as low as 0.4 V and the power conversion efficiency up to 17.33%. The value of V oc loss obtained with this strategy is among the least obtained for similar band gap Pb–Sn low-bandgap perovskite solar cells. Furthermore, the ambient and dark self-stability of the PEAI-treated devices were also enhanced. This work presents a simple doping strategy to mitigate the V oc loss of Pb–Sn mixed low-bandgap perovskite solar cells.

Photovoltaic power-conversion systems can harvest energy from sunlight almost perpetually whenever sun rays are accessible. Meanwhile, as indispensable energy storage units used in advanced technologies such as portable electronics, electric vehicles, and renewable/smart grids, batteries are energy-limited closed systems and require constant recharging. Fusing these two essential technologies into a single device would create sustainable power source. Here, it is demonstrated that such an integrated device can be realized by fusing a rear-illuminated single-junction perovskite solar cell with Li 4 Ti 5 O 12 -LiCoO 2 Li-ion battery, whose photo-charging is enabled by an This article is protected by copyright. All rights reserved. 2 electronic converter via voltage matching. This design facilitates a straightforward monolithic stacking of the battery on the solar cell using a common metal substrate which provides a robust mechanical isolation between the two systems while simultaneously providing an efficient electrical interconnection. This system delivers a high overall photoelectric conversion-storage efficiency of 7.3%, outperforming previous efforts on stackable integrated architectures with organic-inorganic photovoltaics. Furthermore, converter electronics facilitates system control with battery management and maximum power point tracking, which are inevitable for efficient, safe and reliable operation of practical loads. This work represents a significant advancement towards integrated photo-rechargeable energy storage systems as next generation power sources.

Efficient exciton diffusion and charge transport play a vital role in advancing the power conversion efficiency (PCE) of organic solar cells (OSCs). Here, a facile strategy is presented to simultaneously enhance exciton/charge transport of the widely studied PM6:Y6‐based OSCs by employing highly emissive trans‐bis(dimesitylboron)stilbene (BBS) as a solid additive. BBS transforms the emissive sites from a more H‐type aggregate into a more J‐type aggregate, which benefits the resonance energy transfer for PM6 exciton diffusion and energy transfer from PM6 to Y6. Transient gated photoluminescence spectroscopy measurements indicate that addition of BBS improves the exciton diffusion coefficient of PM6 and the dissociation of PM6 excitons in the PM6:Y6:BBS film. Transient absorption spectroscopy measurements confirm faster charge generation in PM6:Y6:BBS. Moreover, BBS helps improve Y6 crystallization, and current‐sensing atomic force microscopy characterization reveals an improved charge‐carrier diffusion length in PM6:Y6:BBS. Owing to the enhanced exciton diffusion, exciton dissociation, charge generation, and charge transport, as well as reduced charge recombination and energy loss, a higher PCE of 17.6% with simultaneously improved open‐circuit voltage, short‐circuit current density, and fill factor is achieved for the PM6:Y6:BBS devices compared to the devices without BBS (16.2%).

as printing fabrication, light weight, flexibility, low toxicity, and short energy payback time. The fused-ring electron acceptors (FREAs) pioneered by the Zhan group have broken through the bottleneck of fullerene acceptors, [1][2][3] and OSCs have achieved revolutionary breakthrough recently. [1][2][3][4][5][6] To date, power conversion efficiencies (PCEs) of FREA-based OSCs have reached 18-19%. [7][8][9][10] Among the diverse FREAs, Y6 (chemical structure shown in Figure S1, Supporting Information) and its derivatives have been widely studied recently due to their high photovoltaic performance. [11][12][13][14] Since most organic semiconductors have low dielectric constants (ε ≈ 3-4), [15] Frenkel excitons with high binding energies (E B ) rather than free charges are generated intrinsically upon photoexcitation. Donor (D)/acceptor (A) interfaces that can provide a driving force for exciton dissociation are essential. [16,17] According to the general consensus developed in fullerene-based OSCs, a bulk heterojunction (BHJ) with D/A phase separation size of around 10-20 nm was the optimal morphology for efficient exciton dissociation and charge transport. [18] Accordingly, most high-efficiency optimized OSCs have In contrast to classical bulk heterojunction (BHJ) in organic solar cells (OSCs), the quasi-homojunction (QHJ) with extremely low donor content (≤10 wt.%) is unusual and generally yields much lower device efficiency.Here, representative polymer donors and nonfullerene acceptors are selected to fabricate QHJ OSCs, and a complete picture for the operation mechanisms of high-efficiency QHJ devices is illustrated. PTB7-Th:Y6 QHJ devices at donor:acceptor (D:A) ratios of 1:8 or 1:20 can achieve 95% or 64% of the efficiency obtained from its BHJ counterpart at the optimal D:A ratio of 1:1.2, respectively, whereas QHJ devices with other donors or acceptors suffer from rapid roll-off of efficiency when the donors are diluted. Through device physics and photophysics analyses, it is observed that a large portion of free charges can be intrinsically generated in the neat Y6 domains rather than at the D/A interface. Y6 also serves as an ambipolar transport channel, so that hole transport as also mainly through Y6 phase. The key role of PTB7-Th is primarily to reduce charge recombination, likely assisted by enhancing quadrupolar fields within Y6 itself, rather than the previously thought principal roles of light absorption, exciton splitting, and hole transport.

Perovskites have been unprecedented with a relatively sharp rise in power conversion efficiency in the last decade. However, the polycrystalline nature of the perovskite film makes it susceptible to surface and grain boundary defects, which significantly impedes its potential performance. Passivation of these defects has been an effective approach to further improve the photovoltaic performance of the perovskite solar cells. Here, we report the use of a novel hydrazine-based aromatic iodide salt or phenyl hydrazinium iodide (PHI) for secondary post treatment to passivate surface and grain boundary defects in triple cation mixed halide perovskite films. In particular, the PHI post treatment reduced current at the grain boundaries, facilitated an electron barrier, and reduced trap state density, indicating suppression of leakage pathways and charge recombination, thus passivating the grain boundaries. As a result, a significant enhancement in power conversion efficiency to 20.6% was obtained for the PHI-treated perovskite device in comparison to a control device with 17.4%.

Solid-state lithium batteries are generally considered as the next-generation battery technology that benefits from inherent nonflammable solid electrolytes and safe harnessing of high-capacity lithium metal. Among various solid-electrolyte candidates, cubic garnet-type Li 7 La 3 Zr 2 O 12 ceramics hold superiority due to their high ionic conductivity (10 –3 to 10 –4 S cm −1 ) and good chemical stability against lithium metal. However, practical deployment of solid-state batteries based on such garnet-type materials has been constrained by poor interfacing between lithium and garnet that displays high impedance and uneven current distribution. Herein, we propose a facile and effective strategy to significantly reduce this interfacial mismatch by modifying the surface of such garnet-type solid electrolyte with a thin layer of silicon nitride (Si 3 N 4 ). This interfacial layer ensures an intimate contact with lithium due to its lithiophilic nature and formation of an intermediate lithium–metal alloy. The interfacial resistance experiences an exponential drop from 1197 to 84.5 Ω cm 2 . Lithium symmetrical cells with Si 3 N 4 -modified garnet exhibited low overpotential and long-term stable plating/stripping cycles at room temperature compared to bare garnet. Furthermore, a hybrid solid-state battery with Si 3 N 4 -modified garnet sandwiched between lithium metal anode and LiFePO 4 cathode was demonstrated to operate with high cycling efficiency, excellent rate capability, and good electrochemical stability. This work represents a significant advancement toward use of garnet solid electrolytes in lithium metal batteries for the next-generation energy storage devices.