Interplay between nucleation and crystal growth during the formation of CH3NH3PbI3 thin films and their application in solar cells

Improved Performance of Perovskite Light-Emitting Diodes by Quantum Confinement Effect in Perovskite Nanocrystals

“…To better realize the nature of strong PL emission in the MAPbBr 3 nanograins formed by the OAB adductive, the excitonic characteristics of the MAPbBr 3 films should be considered. As we reported previously [ 42 ], temperature-dependent photoluminescence (TDPL) can be used to determine the exciton binding energy by linear fitting with a PL spectral broadening equation [ 43 ] at different temperatures: ln(hΔν − hΔν 0 ) = ln(hν T ) − E b /K B T where hΔν is the full width at half maximum (FWHM) of the PL spectrum at some temperature, hΔν 0 is the FWHM of the PL spectrum at the initial temperature, hν T is related to the thermal dissociation rate, E b is the exciton binding energy, K B is the Boltzmann constant, and T is the temperature. The PL spectra at temperatures from 100 to 300 K for the MAPbBr 3 films deposited with (4%) and without (pure) the OAB adductive are shown in Figure 6 .…”

Overcoming the Intrinsic Difference between Hydrophilic CH3NH3PbI3 and Hydrophobic C60 Thin Films to Improve the Photovoltaic Performance

“…Figure 5 a presents the PL spectra of MAPbI 3 /C 60 /ITO/glass samples. When the hot excitons relax to the conduction band from the excited state through rapid thermalization (downhill relaxation), about half of the excitons in the MAPbI 3 thin film can self-dissociate at room temperature and form free carriers, due to the low exciton binding energies [ 6 , 7 , 8 , 9 ]. As the other half of the excitons have to diffuse to the p-n junction interface to generate free carriers, the PL intensity from the residual excitons in the MAPbI 3 thin films can be used to evaluate the exciton dissociation at the interface.…”

“…High-quality organic lead halide perovskites (CH 3 NH 3 PbI 3 , CH 3 NH 3 PbI 3− x Cl x , and CH(NH 2 ) 2 PbI 3 ), which can be fabricated using a two-step or a one-step spin-coating method [ 1 , 2 , 3 , 4 ], have been widely used as the light harvesting material in photovoltaic cells due to their high power conversion efficiency ( PCE ) and low-cost of fabrication. It is well known that the low absorption bandgap (<1.6 eV) [ 5 ], small exciton binding energy (2–70 meV) [ 6 , 7 , 8 , 9 ], long exciton lifetime (>10 ns) [ 10 , 11 , 12 ], high carrier mobility (>5 cm 2 /Vs) [ 13 , 14 ], and long carrier diffusion length (>1 μm) [ 15 , 16 ] of perovskite thin films are the reasons why high-performance photovoltaic cells can be realized. The first use of CH 3 NH 3 PbI 3 (MAPbI 3 ) as a light harvesting material deposited on top of a hydrophilic mesoporous TiO 2 film [ 17 ], resulted in a moderate PCE of 3.81% [ 18 ].…”

“…Therefore, the thin-film quality of the resultant MAPbI 3 perovskites fabricated by the two-step solution method is related to the fabrication environment [ 24 ]. High-quality MAPbI 3 thin films can also be obtained using a one-step solution process with an in situ nonpolar antisolvent washing treatment [ 3 , 4 , 9 ]. Toluene, chlorobenzene, boromobenzene, and iodobenzene have been used as the anti-solvent in the washing treatment process while a mixture of gamma-butyrolactone (GBL) and dimethyl sulfoxide (DMSO), or a mixture of dimethylformamide (DMF) and DMSO was used as the MAPbI 3 precursor solvent.…”

Improving the Quality of CH3NH3PbI3 Films via Chlorobenzene Vapor Annealing

“…Spin coating is an important method to prepare perovskite films. Usually, during spin coating process the non‐dissolving solvents such as chlorobenzene, toluene, or diethyl ether are dropped into the perovskite precursor films to produce high crystallinity and uniform perovskite films . Dropping non‐dissolving solvent can help wash out the residue solvent to form a supersaturated precursor solution, which can preferably control the crystallization of the perovskite films and form uniform films with large crystalline grains.…”