Buried interface molecular hybrid for inverted perovskite solar cells.

Perovskite solar cells (PSCs) with an "inverted" architecture are a key pathway for commercializing this emerging photovoltaic technology due to the better power conversion efficiency (PCE) and operational stability as compared to the "normal" device structure. Specifically, PCEs of the inverted PSCs have exceeded 25% owing to the development of improved self-assembled molecules (SAMs)1-5 and passivation strategies6-8. Nevertheless, poor wettability and agglomerations of SAMs9-12 will cause interfacial losses, impeding further improvement in PCE and stability. Herein, we report on molecular hybrid at the buried interface in inverted PSCs by co-assembling a multiple carboxylic acid functionalized aromatic compound of 4,4',4''-nitrilotribenzoicacid (NA) with a popular SAM of [4-(3,6-dime-thyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) to improve the heterojunction interface. The molecular hybrid of Me-4PACz with NA could substantially improve the interfacial characteristics. The resulting inverted PSCs demonstrated a record-certified steady-state efficiency of 26.54%. Crucially, this strategy aligns seamlessly with large-scale manufacturing, achieving the highest certified PCE for inverted mini-modules at 22.74% (aperture area: 11.1 cm2). Our device also maintained 96.1% of its initial PCE after more than 2,400 hours of 1-sun operation in ambient air.

Thermal-Rectified Gradient Porous Polymeric Film for Solar-Thermal Regulatory Cooling.

Solar-thermal regulation concerning thermal insulation and solar modulation is pivotal for cooling textiles and smart buildings. Nevertheless, a contradiction arises in balancing the demand to prevent external heat infiltration with the efficient dissipation of excess heat from enclosed spaces. Here, a concentration-gradient polymerization strategy is presented for fabricating a gradient porous polymeric film comprising interconnected polymeric microspheres. This method involves establishing an electric field-driven gradient distribution of charged crosslinkers in the precursor solution, followed by subsequent polymerization and freeze-drying processes. The resulting porous film exhibits a significant porosity gradient along its thickness, leading to exceptional unidirectional thermal insulation capabilities with a thermal rectification factor of 21%. The gradient porous film, with its thermal rectification properties, effectively reconciles the conflicting demands of diverse thermal conductivity for cooling unheated and spontaneously heated enclosed spaces. Consequently, the gradient porous film demonstrates remarkable enhancements in solar-thermal management, achieving temperature reductions of 3.0 and 4.1 °C for unheated and spontaneously heated enclosed spaces, respectively, compared to uniform porous films. The developed gradient-structured porous film thus holds promise for the development of thermal-rectified materials tailored to regulate solar-thermal conditions within enclosed environments.

Ionic Liquid-Induced Multisite Synergistic Interactions for Highly Efficient Inverted Perovskite Solar Cells.

The interfacial properties of p-i-n inverted perovskite solar cells (PSCs) play a key role in further improving the photovoltaic performance of PSCs. Herein, multisite synergistic interactions were constructed using ionic liquids (ILs) prepared by mixing urea and choline chloride (ChCl) to substantially improve the interfacial properties of inverted PSCs. Systematically theoretical calculations and experimental studies are comprehensively performed, which reveal that the C═O···Pb2+ coordination interaction, N-H···I hydrogen bond, and Cl-Pb bond could be simultaneously formed between the perovskites and IL, and Ch in IL could interact with the perovskite by occupying the formamidinium site. Meanwhile, -OH/π and -NH/π interactions could be formed between -OH and -NH in IL and the phenyl group in PTAA, respectively. These multisite synergistic interactions are beneficial to improve the perovskite film quality and interfacial properties of inverted PSCs, which could greatly suppress nonradiative recombination within the PSCs. Consequently, the inverted PSCs show an impressive efficiency of 22.4% and an excellent electroluminescence efficiency of 3.7%.

Suppressing Nickel Oxide/Perovskite Interface Redox Reaction and Defects for Highly Performed and Stable Inverted Perovskite Solar Cells.

The inorganic hole transport layer of nickel oxide (NiOx ) has shown highly efficient, low-cost, and scalable in perovskite photovoltaics. However, redox reactions at the interface between NiOx and perovskites limit their commercialization. In this study, ABABr (4-(2-Aminoethyl) benzoic acid bromide) between the NiOx and different perovskite layers to address the issues has been introduced. How the ABABr interacts with NiOx and perovskites is experimentally and theoretically investigated. These results show that the ABABr molecule chemically reacts with the NiOx via electrostatic attraction on one side, whereas on the other side, it forms a strong hydrogen bond via the NH3 + group with perovskites layers, thus directly diminishing the redox reaction between the NiOx and perovskites layers and passivating the layer surfaces. Additionally, the ABABr interface modification leads to significant improvements in perovskite film morphology, crystallization, and band alignment. The perovskites solar cells (PSCs) based on an ABABr interface modification show power conversion efficiency (PCE) improvement by over 13% and maintain over 90% of its PCE after continuous operation at maximum power point for over 500 h. The work not only contributes to the development of novel interlayers for stable PSCs but also to the understanding of how to prevent interface redox reactions.

Ligand exchange engineering of FAPbI3 perovskite quantum dots for solar cells.

Formamidinium lead triiodide (FAPbI3) perovskite quantum dots (PQDs) show great advantages in photovoltaic applications due to their ideal bandgap energy, high stability and solution processability. The anti-solvent used for the post-treatment of FAPbI3 PQD solid films significantly affects the surface chemistry of the PQDs, and thus the vacancies caused by surface ligand removal inhibit the optoelectronic properties and stability of PQDs. Here, we study the effects of different anti-solvents with different polarities on FAPbI3 PQDs and select a series of organic molecules for surface passivation of PQDs. The results show that methyl acetate could effectively remove surface ligands from the PQD surface without destroying its crystal structure during the post-treatment. The benzamidine hydrochloride (PhFACl) applied as short ligands of PQDs during the post-treatment could fill the A-site and X-site vacancies of PQDs and thus improve the electronic coupling of PQDs. Finally, the PhFACl-based PQD solar cell (PQDSC) achieves a power conversion efficiency of 6.4%, compared to that of 4.63% for the conventional PQDSC. This work provides a reference for insights into the surface passivation of PQDs and the improvement in device performance of PQDSCs.

Insight into the Interface Engineering of a SnO2/FAPbI3 Perovskite Using Lead Halide as an Interlayer: A First-Principles Study.

The interfacial properties of the perovskite photovoltaic layer and electron transport layer (ETL) are critical to minimize energy losses of perovskite solar cells (PSCs) induced by interfacial recombination. Herein, the interface engineering of the SnO2/FAPbI3 perovskite using PbX2 (X = Cl, Br, or I) as an interlayer is extensively studied using first-principles calculations. The results reveal that the thickness of the PbI2 interlayer needs to be finely controlled, which may limit charge transport if there is a large amount of PbI2 precipitation at the interface. The high lattice mismatch of the PbBr2 with the SnO2/FAPbI3 interface makes PbBr2 an unfavorable passivation material. Due to the strong coupling of the PbCl2 with both SnO2 and FAPbI3, an efficient electron transport pathway could be built after applying PbCl2 as an interlayer. Meanwhile, the PbCl2 interlayer could also effectively passivate interface defects, therefore lowering the energy losses of PSCs.