Shiang Li

Abstract Benefiting from their simple and cost‐effective fabrication procedures, printable mesoscopic perovskite solar cells (p‐MPSCs) exhibit substantial potential for large‐scale production. In p‐MPSCs, the thickness of the perovskite filled in the TiO 2 and ZrO 2 mesoporous layers is ≈3 µm. Therefore, the perovskite crystallization process is more intricate and challenging in the mesoporous structure than the general planar thin film (0.3–0.5 µm). In this work, a multifunctional fluorinated molecule is applied to work as an additive to improve the perovskite crystallization, enhance the device efficiency, and elevate the operational stability. This additive forms robust coordination between its carbonyl groups and uncoordinated Pb 2+ , thereby effectively passivating defects. The hydrophobic properties of the fluorinated molecule contribute to the device's water‐resistant capability and long‐term operational stability. With these synergistic effects, the power conversion efficiency (PCE) of small‐area cells (0.1 cm 2 ) reaches 20.15% under 1 sun illumination. Large‐area modules (56.4 cm 2 ) are fabricated and exhibit a PCE of 15.41%.

The growth of high-quality tin-based perovskite films remains a grand challenge due to uncontrollable crystallization kinetics. Here, we report a facile strategy to realize an epitaxial-like growth of highly oriented tin-based perovskite films with the assistance of perovskite quantum dots (PQDs). Synchrotron-based in situ X-ray scattering results reveal that PQDs can act as nucleation centers to promote the growth of highly oriented perovskite crystals for both FASnI3 and MASnI3 systems. Remarkably, the degree of lattice strain can be readily modulated by tuning the lattice mismatch between various PQDs and bulk perovskites, thus reducing defect density and improving efficiencies. The efficiency of MASnI3 PSCs with PQDs has been pushed to 12.49%, which is the highest of this type reported so far. Furthermore, the film and device stability are enhanced owing to the improved film quality and the protection of hydrophobic ligands from PQDs.

Abstract The inefficient charge transport and large exciton binding energy of quasi‐2D perovskites pose challenges to the emission efficiency and roll‐off issues for perovskite light‐emitting diodes (PeLEDs) despite excellent stability compared to 3D counterparts. Herein, alkyldiammonium cations with different molecular sizes, namely 1,4‐butanediamine (BDA), 1,6‐hexanediamine (HDA) and 1,8‐octanediamine (ODA), are employed into quasi‐2D perovskites, to simultaneously modulate the injection efficiency and recombination dynamics. The size increase of the bulky cation leads to increased excitonic recombination and also larger Auger recombination rate. Besides, the larger size assists the formation of randomly distributed 2D perovskite nanoplates, which results in less efficient injection and deteriorates the electroluminescent performance. Moderate exciton binding energy, suppressed 2D phases and balanced carrier injection of HDA‐based PeLEDs contribute to a peak external quantum efficiency of 21.9%, among the highest in quasi‐2D perovskite based near‐infrared devices. Besides, the HDA‐PeLED shows an ultralong operational half‐lifetime T 50 up to 479 h at 20 mA cm ‒2 , and sustains the initial performance after a record‐level 30 000 cycles of ON–OFF switching, attributed to the suppressed migration of iodide anions into adjacent layers and the electrochemical reaction in HDA‐PeLEDs. This work provides a potential direction of cation design for efficient and stable quasi‐2D‐PeLEDs.

Abstract Despite the rapid development of perovskite solar cells (PSCs) in the past decade, the open‐circuit voltage ( V OC ) of PSCs still lags behind the theoretical Shockley–Queisser limit. Energy‐level mismatch and unwanted nonradiative recombination at key interfaces are the main factors detrimental to V OC . Herein, a perovskite crystallization‐driven template is constructed at the SnO 2 /perovskite buried interface through a self‐assembled amphiphilic phosphonate derivative. The highly oriented supramolecular template grows from an evolutionary selection growth via solid–solid phase transition. This strategy induces perovskite crystallization into a highly preferred (100) orientation toward out‐of‐plane direction and facilitated carrier extraction and transfer due to the elimination of energy barrier. This self‐assembly process positively passivates the intrinsic surface defects at the SnO 2 /perovskite interface through the functionalized moieties, a marked contrast to the passive effect achieved via incidental contacts in conventional passivation methods. As a result, PSCs with buried interface modification exhibit a promising PCE of 25.34%, with a maximum V OC of 1.23 V, corresponding to a mere 0.306 V deficit (for perovskite bandgap of 1.536 eV), reaching 97.2% of the theoretical V OC limit. This strategy spontaneously improves the long‐term operational stability of PSCs under thermal and moisture stress (ISOS‐L‐3: MPP, 65 °C, 50% RH, T 92 lifetime exceeding 1200 h).