No abstract

The double perovskite Cs 2 AgBiBr 6 single crystal holds great potential for detecting applications because of its low minimum detectable dose rate and toxic-free merit. Nevertheless, the disordered arrangement of Ag + /Bi 3+ usually gives rise to unexpected structural distortion and thereafter heavily influences the photoelectric properties of the Cs 2 AgBiBr 6 single crystal. Herein, phenylethylamine bromide is demonstrated to be capable of in situ regulation of the order-disorder phase transition in the Cs 2 AgBiBr 6 single crystal. The improved ordering extent of alternatively arranged [AgX 6 ] 5− and [BiX 6 ] 3− octahedra is theoretically and experimentally proven to decrease the defect density and suppress self-trapped exciton formation, and thereby tune the band gap and enhance the carrier mobility, which consequently promotes its application in an X-ray detector. The performance of a corresponding detector based on PEA-Cs 2 AgBiBr 6 single crystal displays superior performances, e.g., longer carrier drift distance, higher photoconductive gain, and faster current response (13 vs 3190 µs). Prominently, the as-fabricated PEA-Cs 2 AgBiBr 6 single-crystal X-ray detector has an extremely high sensitivity with a value of 288.8 µC Gy air −1 cm −2 under a bias of 50 V (22.7 V mm −1 ), which largely outperforms those of their counterparts with lower ordering structure.

Lewis base molecules that bind undercoordinated lead atoms at interfaces and grain boundaries (GBs) are known to enhance the durability of metal halide perovskite solar cells (PSCs). Using density functional theory calculations, we found that phosphine-containing molecules have the strongest binding energy among members of a library of Lewis base molecules studied herein. Experimentally, we found that the best inverted PSC treated with 1,3-bis(diphenylphosphino)propane (DPPP), a diphosphine Lewis base that passivates, binds, and bridges interfaces and GBs, retained a power conversion efficiency (PCE) slightly higher than its initial PCE of ~23% after continuous operation under simulated AM1.5 illumination at the maximum power point and at ~40°C for >3500 hours. DPPP-treated devices showed a similar increase in PCE after being kept under open-circuit conditions at 85°C for >1500 hours.

The development of highly stable and efficient wide-bandgap (WBG) perovskite solar cells (PSCs) based on bromine-iodine (Br–I) mixed-halide perovskite (with Br greater than 20%) is critical to create tandem solar cells. However, issues with Br–I phase segregation under solar cell operational conditions (such as light and heat) limit the device voltage and operational stability. This challenge is often exacerbated by the ready defect formation associated with the rapid crystallization of Br-rich perovskite chemistry with antisolvent processes. We combined the rapid Br crystallization with a gentle gas-quench method to prepare highly textured columnar 1.75–electron volt Br–I mixed WBG perovskite films with reduced defect density. With this approach, we obtained 1.75–electron volt WBG PSCs with greater than 20% power conversion efficiency, approximately 1.33-volt open-circuit voltage ( V oc ), and excellent operational stability (less than 5% degradation over 1100 hours of operation under 1.2 sun at 65°C). When further integrated with 1.25–electron volt narrow-bandgap PSC, we obtained a 27.1% efficient, all-perovskite, two-terminal tandem device with a high V oc of 2.2 volts.

Van der Waals forces, usually own lower decomposition activation energy and high freedom degree of ions migration, which inevitably leads to inferior stability of 3D perovskite itself. [7][8][9] In addition, the neutral iodine atoms are easily pushed forward into the nearby lattice to form a large number of iodine vacancies, relying on the decoupling of electrons and holes. [10] Distinct from the band-like nature of the high-mobility electronic transport in perovskite material, the ionic migration exhibits obvious hopping conduction with varying activation energies under external environment. [11,12] In this scenario, structure-induced ion migration has a detrimental role in the perovskite decomposition and thereafter quenching the performance of solar cells.In the structure of perovskites, the basic building blocks of [PbX 6 ] 4− octahedra are organized in different ways to exhibit 0D, 1D, 2D, and 3D structures. [13][14][15][16] It should be noted that, here, the 2D, 1D, and 0D perovskites on molecular level definitions are different from the morphological 2D nanosheets, 1D nanowires, and 0D nanoparticles based on 3D APbX 3 that were reported elsewhere. [17,18] Particularly, the 2D multilayered halide perovskites are attained by stacking n perovskite layers along the [h00] direction of the archetypal 3D structure, spaced out by long separated ammonium cations. The unit layers are stacked together by a combination force of hydrophobic and/or Coulombic to maintain the structure integrity. [19] Recently, the 2D and/or 2D-3D halide PSCs emerged as a promising class of stable and efficient devices, which enable to realize the efficiency as high as 16.92% and 22.1% for 2D and 2D-3D halide PSCs, respectively. [20,21] Following this line of thought, the 1D perovskites have the [PbX 6 ] 4− octahedra structurally linked in a 1D chain that may share the corner, edge, or face, and the A-site organic cations were interleaved among the octahedra. [22,23] The structural dimensionalities of 1D perovskites can be single-chain (n = 1), double-chains (n = 2), triple-chains, and infinite-chains (n = ∞) edge/face-shared [PbX 6 ] 4− octahedra, respectively. Generally, 1D organic metal halides with corner/edge/face-shared [PbX 6 ] 4− octahedra have higher stability than 3D organic-inorganic metal halides, which could be associated with its structural merits: i) the linearly arranged [PbX 6 ] 4− by means of "shoulder to shoulder" can improve the skeleton strength of The stability of perovskite solar cells (PSCs) has been identified to be the bottleneck toward their industrialization. With the aim of tackling this challenge, a 1D PbI 2 -bipyridine (BPy)(II) perovskite is fabricated, which is shown to be capable of in situ assembly of a 1D@3D perovskite that is promoted by a PbI 2 -dimethyl sulfoxide complex with a skeletal linear chain structure. The as-prepared 1D@3D perovskite is observed to demonstrate extremely high stability under external large electric fields in humid environments by means of an in situ characterization technique...