A simple strategy is provided to construct novel supramolecular hydrogels with both self-healing and shape memory properties. Starting from achieving self-healable hydrogel based on the dynamic interactions of phenylboronic acid modified sodium alginate (Alg-PBA) and poly(vinyl alcohol) (PVA), further formation of a complex of alginate with Ca(2+) renders this hydrogel with the capability of shape memory at the macro-/microscopic scales.

Low-toxicity tin-based perovskites have exhibited huge potential for photovoltaics applications. However, the facile oxidation of Sn2+ to Sn4+ induces ubiquitous Sn vacancies and p-type doping in perovskite films. In addition, the fast crystallization easily leads to poor film morphology and high defect concentration. In this work, we developed a film-formation strategy via the fluoro-aniline isomers medium and achieved the simultaneous restriction of Sn2+ oxidation and regulation of crystallization. The ortho-fluorine ligand, which exhibits unidirectional and bent geometry at the surface, could contribute to the lattice robustness with better restriction of Sn vacancy formation, compared with the bidirectional and vertical ligands. The resulting perovskite solar cell (PSC) device modified by 2-F-PEA shows a considerable PCE of 10.17% (certified 8.58%), with an efficiency attenuation of less than 15% under 1600 h of light aging testing. Our findings could provide a new avenue for the enhancement of both efficiency and stability of tin-based PSCs.

Built-in field and energy band alignment decide the charge separation and transportation in perovskite solar cells. Composition change in perovskites to tune the energy states is thus valuable to try. In contrast to the equivalent substitution of Pb, here trivalent Sb is for the first time incorporated into CH3NH3PbI3, with a tuned optical band gap from 1.55 to 2.06 eV. Density function theory (DFT) calculations unveil the enlarged energy band gap and n-type doping property by Sb with more valence electrons than Pb. n-Type doping by Sb elevates the quasi-Fermi energy level of the perovskite/TiO2 and promotes electron transport in the working solar cell. Thus, the doped perovskite solar cell gains a lot in photovoltage while maintaining a high photocurrent, resulting in enhanced performance of 15.6% (0.956 sun, AM1.5). The results highlight the method of n/p-type doping of perovskites by heterovalent elements and its tunability to the energy states.

Interfacial ligand passivation engineering has recently been recognized as a promising avenue, contributing simultaneously to the optoelectronic characteristics and moisture/operation tolerance of perovskite solar cells. To further achieve a win-win situation of both performance and stability, an innovative conjugated aniline modifier (3-phenyl-2-propen-1-amine; PPEA) is explored to moderately tailor organolead halide perovskites films. Here, the conjugated PPEA presents both "quasi-coplanar" rigid geometrical configuration and distinct electron delocalization characteristics. After a moderate treatment, a stronger dipole capping layer can be formed at the perovskite/ transporting interface to achieve favorable banding alignment, thus enlarging the built-in potential and promoting charge extraction. Meanwhile, a conjugated cation coordinated to the surface of the perovskite grains/units can form preferably ordered overlapping, not only passivating the surface defects but also providing a fast path for charge exchange. Benefiting from this, a ≈21% efficiency of the PPEA-modified solar cell can be obtained, accompanied by long-term stability (maintaining 90.2% of initial power conversion efficiency after 1000 h testing, 25 °C, and 40 ± 10 humidity). This innovative conjugated molecule "bridge" can also perform on a larger scale, with a performance of 18.43% at an area of 1.96 cm 2 .

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Passivating undercoordinated ions is an effective way to reduce the defect densities at the surface and grain boundaries (GBs) of perovskite materials for enhanced photovoltaic performance and stability of perovskite solar cells (PSCs). Here, (BBF) complex is chosen as a multifunctional additive, which contains both C7H9N and BF3 groups working as Lewis base and Lewis acid, respectively, can bond with Pb2+/I− and FA+ on the surface and in the GBs in the perovskite film, affording passivation of both cation and anion defects. The synergistic effect of the C7H9N and BF3 complex slows the crystallization during the perovskite film deposition to improve the crystalline quality, which reduces the trap density and the recombination in the perovskite film to suppress nonradiative recombination loss and minimizes moisture permeation to improve the stability of the perovskite material. Meanwhile, such an additive improves the energy-level alignment between the valence band of the perovskite and the highest occupied molecular orbital of the hole-transporting material, Spiro-OMeTAD. Consequently, our work achieves power conversion efficiency of 23.24%, accompanied by enhanced stability under ambient conditions and light illumination and opens a new avenue for improving the performance of PSCs through the use of a multifunctional complex.

The halide perovskite Ruddlesden−Popper (RP) phases are a homologous layered subclass of solution-processable semiconductors that have aroused great attention, especially for developing long-term solar photovoltaics. They are defined as (A′) 2 (A) n−1 Pb n X 3n+1 (A′ = spacer cation, A = cage cation, and X = halide anion). The orientation control of low-temperature selfassembled thin films is a fundamental issue associated with the ability to control the charge carrier transport perpendicular to the substrate. Here we report new chemical derivatives designed from a molecular perspective using a novel spacer cation 3-phenyl-2-propenammonium (PPA) with conjugated backbone as a lowtemperature strategy to assemble more efficient solar cells. First, we solved and refined the crystal structures of single crystals with the general formula (PPA) 2 (FA 0.5 MA 0.5 ) n−1 Pb n I 3n+1 (n = 2 and 3, space group C2) using X-ray diffraction and then used the mixed halide (PPA) 2 (Cs 0.05 (FA 0.88 MA 0.12 ) 0.95 ) n−1 Pb n (I 0.88 Br 0.12 ) 3n+1 analogues to achieve more efficient devices. While forming the RP phases, multiple hydrogen bonds between PPA and inorganic octahedra reinforce the layered structure. For films we observe that as the targeted layer thickness index increases from n = 2 to n = 4, a less horizontal preferred orientation of the inorganic layers is progressively realized along with an increased presence of high-n or 3D phases, with an improved flow of free charge carriers and vertical to substrate conductivity. Accordingly, we achieve an efficiency of 14.76% for planar p−i−n solar cells using PPA-RP perovskites, which retain 93.8 ± 0.25% efficiency with encapsulation after 600 h at 85 °C and 85% humidity (ISOS-D-3).

Recently, low temperature solution-processed tin oxide (SnO) as a versatile electron transport layer (ETL) for efficient and robust planar heterojunction (PH) perovskite solar cells (PSCs) has attracted particular attention due to its outstanding properties such as high optical transparency, high electron mobility, and suitable band alignment. However, for most of the reported works, an annealing temperature of 180 °C is generally required. This temperature is reluctantly considered to be a low temperature, especially with respect to the flexible application where 180 °C is still too high for the polyethylene terephthalate flexible substrate to bear. In this contribution, low temperature (about 70 °C) UV/ozone treatment was applied to in situ synthesis of SnO films deposited on the fluorine-doped tin oxide substrate as ETL. This method is a facile photochemical treatment which is simple to operate and can easily eliminate the organic components. Accordingly, PH PSCs with UV-sintered SnO films as ETL were successfully fabricated for the first time. The device exhibited excellent photovoltaic performance as high as 16.21%, which is even higher than the value (11.49%) reported for a counterpart device with solution-processed and high temperature annealed SnO films as ETL. These low temperature solution-processed and UV-sintered SnO films are suitable for the low-cost, large yield solution process on a flexible substrate for optoelectronic devices.