Crystal system: orthorhombic
| Temperature, K | Photoluminescence peak position, eV |
|---|
Starting materials: Methylamine (40% in methanol), hydroiodic acid (57 wt% in water), PbI2, g-butyrolactone, H2O2, NH4OH, Si wafer
Product: MAPbI3 film
Description: React 30 mL of methylamine and 32.3 mL of hydroiodic acid at 0 °C for 2 h. Evaporate solvents at 50 °C. Wash the yellowish raw CH3NH3I with diethyl ether by stirring the solution for 30min for a total of three times. Recrystallize CH3NH3I from a mixed solvent of diethyl ether and ethanol. Collect the solid and dry at 60 °C in a vacuum oven for 24 h. Treat Si wafer with an aqueous solution of H2O2 and NH4OH with a volume ratio of H2O2 : NH4OH : H2O = 1 : 1 : 5 for 30 min. Drop a 40 wt% precursor solution of equimolar CH3NH3I and PbI2 in g-butyrolactone onto the Si wafer to form the MAPbI3 film. Spin-coat at 1500 rpm for 30 s, and then at 2500 rpm for 40 min in air. Upon drying at room temperature, color change indicates the formation of MAPbI3 in the solid state. Anneal the MAPbI3 film in air for 15 min at 100 °C.
Method: Photoluminescence
Description: Steady-state and time-resolved PL spectra were measured using an Edinburgh FLS920 spectroscopy system using laser excitation at 405 nm. PL peak is due to near-band edge transition. [Results and discussion paragraph 3; Fig. 2(b) Peak_OI]
Comment: Grain size were 100-500 nm diameter
Crystal system: tetragonal
| Temperature, K | Photoluminescence peak position, eV |
|---|
Starting materials: Methylamine (40% in methanol), hydroiodic acid (57 wt% in water), PbI2, g-butyrolactone, H2O2, NH4OH, Si wafer
Product: MAPbI3 film
Description: React 30 mL of methylamine and 32.3 mL of hydroiodic acid at 0 °C for 2 h. Evaporate solvents at 50 °C. Wash the yellowish raw CH3NH3I with diethyl ether by stirring the solution for 30min for a total of three times. Recrystallize CH3NH3I from a mixed solvent of diethyl ether and ethanol. Collect the solid and dry at 60 °C in a vacuum oven for 24 h. Treat Si wafer with an aqueous solution of H2O2 and NH4OH with a volume ratio of H2O2 : NH4OH : H2O = 1 : 1 : 5 for 30 min. Drop a 40 wt% precursor solution of equimolar CH3NH3I and PbI2 in g-butyrolactone onto the Si wafer to form the MAPbI3 film. Spin-coat at 1500 rpm for 30 s, and then at 2500 rpm for 40 min in air. Upon drying at room temperature, color change indicates the formation of MAPbI3 in the solid state. Anneal the MAPbI3 film in air for 15 min at 100 °C.
Method: Photoluminescence
Description: Steady-state and time-resolved PL spectra were measured using an Edinburgh FLS920 spectroscopy system using laser excitation at 405 nm. PL peak is due to the near-band-edge transition. Refer to Results and discussion paragraph 2; Fig. 2(a) Peak_T.
Comment: Grain size were: 100-500 nm diameter
Crystal system: orthorhombic
| Photoluminescence peak position, eV |
|---|
Starting materials: PbI2, dimethylformamide, quartz substrate, CH3NH3I (in 0.06 M 2-propanol)
Product: MAPbI3 film
Description: Deposit 1.0 M solution of PbI2 (L0279 for the perovskite precursor, Tokyo Chemical Industry Co. Ltd., Japan) in dehydrated dimethylformamide at 70 °C on a quartz substrate by spin-coating (slope 5 s, 6500 rpm, 5 s, slope 5 s). Anneal the resulting yellow film on a hot plate at 70 °C for 1 h. Dip the PbI2 film in a 0.06 M 2-propanol solution of CH3NH3I (Tokyo Chemical Industry Co., Ltd., Japan) for 40 s. Anneal the formed perovskite film on a hot plate at 70 °C for 1 h. Keep the samples in vacuum at RT for several days before the optical measurements; this process helps to reduce significantly the unreacted PbI2 and subsequently improves the quality of thin film samples.
Method: Photoluminescence
Description: PL measurements were based on a Yb:KGW regenerative amplified laser (pulse duration: ∼300 fs; repetition rate: 50−100 kHz) with 1.8 eV photoexcitation. O-PL peak emerged under strong fluences. Refer to Page 2317 paragraph 3; Figure 1. (a) O-PL.
Comment: Orthorhombic phase contribution towards PL.
Crystal system: orthorhombic
| Photoluminescence peak position, eV |
|---|
Starting materials: PbI2, dimethylformamide, quartz substrate, CH3NH3I (in 0.06 M 2-propanol)
Product: MAPbI3 film
Description: Deposit 1.0 M solution of PbI2 (L0279 for the perovskite precursor, Tokyo Chemical Industry Co. Ltd., Japan) in dehydrated dimethylformamide at 70 °C on a quartz substrate by spin-coating (slope 5 s, 6500 rpm, 5 s, slope 5 s). Anneal the resulting yellow film on a hot plate at 70 °C for 1 h. Dip the PbI2 film in a 0.06 M 2-propanol solution of CH3NH3I (Tokyo Chemical Industry Co., Ltd., Japan) for 40 s. Anneal the formed perovskite film on a hot plate at 70 °C for 1 h. Keep the samples in vacuum at RT for several days before the optical measurements; this process helps to reduce significantly the unreacted PbI2 and subsequently improves the quality of thin film samples.
Method: Photoluminescence
Description: PL measurements were based on a Yb:KGW regenerative amplified laser (pulse duration: ∼300 fs; repetition rate: 50−100 kHz) with 1.8 eV photoexcitation. T-PL peak visible at low fluences. Refer to Page 2317 paragraph 3; Figure 1. (a) T-PL.
Comment: PL contribution due to low-temperature tetragonal phase