How to Make Dense and Flat Perovskite Layers for >20% Efficient Solar Cells: Oriented, Crystalline Perovskite Intermediates and Their Thermal Conversion

Abstract

CH 3 NH 3 PbI 3 (MAPbI 3) perovskite layers can be obtained by thermal annealing thin films of the intermediate dimethyl sulfoxide (DMSO) intercalated complex, MA 2 Pb 3 I 8 ¢2DMSO. In the present work, the formation, structure, and thermal transformation of the intermediate complex in both bulk and thin film form is examined in detail. The grain size and orientation of the intermediate crystallites in the solvent-intercalated thin film material is shown to directly influence the flatness of the annealed perovskite layer. Flat-lying orientation of the small needle-like intermediate crystallites is found to yield dense and flat perovskite layers. Optimized spin coating and annealing processes are developed for the formation and thermal conversion, respectively, of the intermediate film. Based on these methods, MAPbI 3 perovskite solar cells with high power conversion efficiency (maximum ³20.3%) were obtained with high reproducibility.

Starburst Carbazole Derivatives as Efficient Hole Transporting Materials for Perovskite Solar Cells

“…The energy‐level data are compiled in Table 1. Both the HOMO and LUMO energy levels are higher than the corresponding valance bands (VBs) and conduction bands (CBs) of typical perovskite materials such as MAPbI 3 (MA: methylammonium, VB = −5.45 eV, CB = −3.90 eV) [ 49 ] or Cs 0.05 FA 0.80 MA 0.15 PbI 2.75 Br 0.25 (FA: formamidinium, VB = −5.56 eV, CB = −3.99 eV). [ 50 ] Therefore, efficient hole extraction and electron blocking should be expected.…”

Performance evaluation of mixed-halide perovskites in p-i-n solar cells with a monolayer-based hole transport layer

“…The perovskite solar cells are fabricated on ITO glass substrates following the methods outlined in the supporting information which are based on the processes elaborated in our previous reports. [39][40][41] Each device has an active (masked) area of 0.1 cm 2 . Cross-sectional SEM images (Fig.…”

Hole-Transporting Polymers Containing Partially Oxygen-Bridged Triphenylamine Units and Their Application for Perovskite Solar Cells

“…A mesoporous TiO 2 was prepared on top of compact TiO 2 layer by spin-coating at 5000 rpm using a diluted commercially available precursor paste (PST-18NR) in ethanol (1:5, weight ratio). The perovskite films were prepared from CH 3 NH 3 PbI 3 stock solution (1.1 M in DMSO) [41]. The substrate was first spun at 1000 rpm for 40 s by a slope of 1s, waited for 30 s at 0 rpm, and then spun at 5000 rpm by a slope of 5 s. During the spin-coating after 92 s, 0.5 mL of anhydrous toluene was carefully dropped onto the substrate till the substrate become transparent.…”

“…Device fabrication and photovoltaic properties P1-P4 were used as HTMs in regular-type, mesoporous PSCs. For comparison, reference devices with PTAA were also fabricated [41][42][43]. The device structure was FTO/compact TiO 2 (c-TiO 2 )/mesoporous TiO 2 (mp-TiO 2 )/CH 3 NH 3 PbI 3 / [HTM]/Au.…”