Antisolvent engineering is one of the most widely used methods to obtain high quality perovskite films. This process involves the heavy use of toxic antisolvents, such as toluene (Tol) and chlorobenzene (CB). It is thus highly desirable to develop green antisolvents for the future manufacturing of perovskites. Though several green antisolvents have been developed for iodide perovskites, there are few reports about their application on bromide ones. Besides, the reported green antisolvents for iodide perovskites usually lead to a significant increase in the crystal size, which is not suitable for light emission due to reduced carrier confinement and radiative recombination. Here, we introduce green antisolvent ethyl acetate (EA) to prepare CH3NH3PbBr3 (MAPbBr3) perovskite films. In contrast to previously reported iodide perovskites, EA engineered MAPbBr3 only shows a slight increase in the crystal size. A systematic study on the structural, morphological, and optoelectronic properties of MAPbBr3 prepared with Tol, CB, and EA was carried out. With the benefits of relatively high polarity and low boiling point compared with Tol and CB, EA could extract the solvent more efficiently. This gives rise to MAPbBr3 films with increased crystallinity, improved morphology, and reduced defects, boosting the performance of the corresponding light emitting diodes (LEDs). Our study provides an environmentally friendly way to the manufacturing of efficient MAPbBr3 perovskite LEDs as well as other optoelectronic devices.

The performance of hybrid perovskite solar cells (PSCs) is significantly influenced by the crystallization and morphology of perovskite films. Herein, a novel method of CsPbBr 3 quantum dots (QDs) assisted nucleation is applied to prepare high quality solution-processed methylammonium lead iodide (MAPbI 3 ) films by employing CsPbBr 3 QDs as an additive into diethyl ether anti-solvent. The appropriate amount of CsPbBr 3 QDs can act as effective heterogeneous nucleation centers, leading to the formation of smooth and pinhole-free perovskite films with increased grain size. Furthermore, the growth direction of MAPbI 3 grains is regulated by CsPbBr 3 QDs, exhibiting preferential orientation of (110) plane. Therefore, the MAPbI 3 films with CsPbBr 3 QDs modification show reduced defects and increased carrier lifetime. As a result, the champion PSC with a maximum power conversion efficiency (PCE) up to 20.17% is achieved and 85% of its initial PCE is maintained after aging 1000 h at room temperature under a relative humidity of 50%. This work demonstrates a feasible way to prepare high quality perovskite films for optoelectronic applications.

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The efficiency of perovskite light emitting diodes (PeLEDs) is crucially limited by leakage current and nonradiative recombination. Here we introduce n-butyl amine (BA) to modulate the growth of perovskite films as well as improve the performance of PeLEDs, and investigate in detail the effects of BA incorporation on the structural, optical, and electrical characteristics of perovskite films. The results indicate that BA would terminate the grain surface and inhibit crystal growth, leading to increased radiative recombination. However, BA overload would make the films loose and recreate shunt paths. The electrical detriment of BA overload outweighs its optical benefit. As a result, optimal PeLEDs can be obtained only with moderate BA incorporation.