The modified multi-step thermal annealing process for highly efficient MAPbI3-based perovskite solar cells

Controlled Growth of Large Grains in CH3NH3PbI3 Perovskite Films Mediated by an Intermediate Liquid Phase without an Antisolvent for Efficient Solar Cells

“…Figure a shows the X-ray diffraction (XRD) patterns of the CH 3 NH 3 PbI 3 perovskite film prepared from the perovskite precursor solution with different amounts of the MACl additive. From the XRD patterns in the Bragg–Brentano geometry, two dominant diffraction peaks at 14.1 and 28.4° are observed for all perovskite films, corresponding to the reflections from the (110) and (220) lattice planes, respectively, similar to the previously reported tetragonal CH 3 NH 3 PbI 3 perovskite phase . There is no noticeable shift of the peak at (110), as shown in Figure b, revealing that adding MACl in the perovskite precursor does not have a significant effect on the CH 3 NH 3 PbI 3 perovskite crystal structure.…”

“…From the XRD patterns in the Bragg−Brentano geometry, two dominant diffraction peaks at 14.1 and 28.4°are observed for all perovskite films, corresponding to the reflections from the (110) and (220) lattice planes, respectively, similar to the previously reported tetragonal CH 3 NH 3 PbI 3 perovskite phase. 43 There is no noticeable shift of the peak at (110), as shown in Figure 3b, revealing that adding MACl in the perovskite precursor does not have a significant effect on the CH 3 NH 3 PbI 3 perovskite crystal structure. By increasing the amount of MACl in the perovskite precursor, the intensity of the characteristic (110) and (220) peaks significantly increases and reaches a maximum at 2% MACl, indicating improved crystallization quality, which is consistent with the morphology evolution, as discussed earlier.…”

Advances in Lead-Free Perovskite Single Crystals: Fundamentals and Applications

“…In early 2015, a few years after the perovskite boom in photovoltaics, it was realized that the optimized perovskite thickness in all the high-efficiency solar cells reported as of then (∼300 nm) was essentially limited by the grain size of MAPbI 3 (MA: methylammonium, (CH 3 NH 3 ) + ) polycrystalline films grown by standard thermal annealing. Although thicker MAPbI 3 films were required to enhance the absorption close to the band edge, simply increasing the annealing time for large grain size failed to produce this result as perovskites tend to decompose over time. − A solvent-annealing method was then used, and the crystals grew to micron range, comparable to the film thickness. , This drastic elimination of grain boundaries in the direction of charge transport resulted in a significant reduction in recombination losses and could achieve carrier diffusion lengths of the order of several microns. This work was closely followed by several similar initiatives where good quality, millimeter-sized crystals with internal quantum efficiency ∼100% were produced through top-seeded solution-growth methods.…”

Multi-Scalable Grain Growth via Phenyl-C60-Butyric Acid Methyl Ester Molecular Aggregation in Perovskite Solar Cells

“…25,26 To confirm the size distribution of PCBM aggregates in PCBM−Tol depending on the temperature, DLS measurements were carried out with three different temperatures: 75, 50, and 25 °C. It is well known that large PCBM aggregate effectively inhibits solvent evaporation of the perovskite precursor, thereby allowing the perovskite crystals to grow slowly into large grains during the annealing process and vice versa (Figure 2a); 18,27 therefore, large grains are expected for films processed with low-temperature PCBM solution. To investigate this grain size variation of perovskites as influenced by the PCBM−Tol solution temperature, we measured SEM and AFM of resulting perovskite films, as shown in Figure 2.…”