ABSTRACT
Novel all-inorganic Sn-Pb alloyed perovskites are developed aiming for low toxicity, low bandgap, and long-term stability. Among them, CsPb1- x Snx I2 Br is predicted as an ideal perovskite with favorable band gap, but previously is demonstrated unable to convert to perovskite phase by thermal annealing. In this report, a series of CsPb1- x Snx I2 Br perovskites with tunable bandgaps from 1.92 to 1.38 eV are successfully prepared for the first time via low annealing temperature (60 °C). Compared to the pure CsPbI2 Br, these Sn-Pb alloyed perovskites show superior stability. Furthermore, a novel α-phase-stabilization mechanism of the inorganic Sn-Pb alloyed perovskite by reconfiguring the perovskite crystallization process with chloride doping is provided. Simultaneously, a dense protection layer is formed by the coordination reaction between the surface lead dangling bonds and sulfate ion to retard the permeation of external oxygen and moisture, leading to less oxidation of Sn2+ in perovskite film. As a result, the fabricated all-inorganic Sn-Pb perovskite solar cells (PSCs) show a champion power conversion efficiency of 10.39% with improved phase stability and long-term ambient stability against light, heat, and humidity. This work provides a viable strategy in fabricating high-performance narrow-bandgap all-inorganic PSCs.
ABSTRACT
Dramatic development in perovskite solar cells (PSCs) and the widespread application of wearable electronics have attracted extensive research in the area of large-scale flexible solar power sources based on PSCs. Manufacturing of flexible PSCs by printing is considered to be one of the most potential methods. However, it is still a great challenge to print large-area uniform hole transport layers (HTLs) on a rough and soft plastic substrate to achieve flexible PSCs with high efficiency and good stability. Herein, we synthesized a viscous poly(3,4-ethylene dioxythiophene):graphene oxide (PEDOT:GO) gel and then blade-coated the gel by high-speed shearing to achieve high-quality HTLs with scalable size. The glued HTLs exhibit high viscosity, electrical conductivity, and mechanical flexibility, which enhance the adhesive ability and protect the brittle ITO electrode and perovskite crystals. Due to the gelatinous HTLs, we achieved an optimal efficiency of the flexible PSCs (1.01 cm2) of 19.7%, while that of the large-area flexible perovskite module (25 cm2) exceeded 10%. This is the highest efficiency for reported flexible MAPbI3 PSCs (1.01 cm2). Furthermore, the efficiency retention of the PSCs remains over 85% after 5000 bending cycles, which is of great significance for the practical application of PSCs in portable and wearable electronics.
ABSTRACT
Inkjet printing method is one of the most effective ways for fabricating large-area perovskite solar cells (PSCs). However, because ink crystallizes rapidly during printing, the printed perovskite film is discontinuous with increasing defects. It severely restricts the application of the inkjet printing technology to the fabrication of perovskite photovoltaic devices. Here, we designed a new mixed-cation perovskite ink system that can controllably retard the crystallization rate of perovskite. In this new ink system, the printing solvent is composed of n-methyl pyrrolidone (NMP) and dimethyl formamide (DMF), and PbX2 is replaced by PbX2-DMSO (X = Br, I) complex as a printing precursor to create a high-quality perovskite layer. Accordingly, the printed Cs0.05MA0.14FA0.81PbI2.55Br0.45 perovskite film exhibited high homogeneity with a large grain size (over 500 nm). Besides, the printed perovskite film possessed lower defects with improved carrier lifetime compared to the control sample. Combining these advantages, the printed PSC delivers decent power conversion efficiencies (PCEs) of 19.6% (0.04 cm2) and 17.9% (1.01 cm2). The large-area device can still retain its original efficiency of 89% when stored in air with humidity less than 20% for 1000 h.
ABSTRACT
1,4-butanediamine (BEA) is incorporated into FASnI3 (FA=formamidinium) to develop a series of lead-free low-dimensional Dion-Jacobson-phase perovskites, (BEA)FAn-1 Snn I3n+1 . The broadness of the (BEA)FA2 Sn3 I10 band gap appears to be influenced by the structural distortion owing to high symmetry. The introduction of BEA ligand stabilizes the low-dimensional perovskite structure (formation energy ca. 106 â j mol-1 ), which inhibits the oxidation of Sn2+ . The compact (BEA)FA2 Sn3 I10 dominated film enables a weakened carrier localization mechanism with a charge transfer time of only 0.36â ps among the quantum wells, resulting in a carrier diffusion length over 450â nm for electrons and 340â nm for holes, respectively. Solar cell fabrication with (BEA)FA2 Sn3 I10 delivers a power conversion efficiency (PCE) of 6.43 % with negligible hysteresis. The devices can retain over 90 % of their initial PCE after 1000â h without encapsulation under N2 environment.
