The formation of perovskite multiple quantum well structures for high performance light-emitting diodes

Recent works showed that high efficient perovskite light-emitting diodes can be achieved from solution-processed, self-organized multiple quantum wells (MQWs) with an energy cascade. We investigate how the mixing of QWs with different band gaps can affect the perovskite LED device performance. We find that the annealing process can significantly affect the constitution of the MQWs films, where the dominant phase can evolve from large band gap QWs to small band gap QWs. The optimal constitution for LED application lies in a transition point of small-n QWs dominant phase to large-n QWs dominant phase, when the MQW film presents highest photoluminescence while still remains uniform film morphology. Perovskite LEDs: annealing nails itSimple thermal annealing up to 100 degree Celsius leads to optimal device efficiency for mixed-cation halide perovskite light-emitting diodes. A team led by Prof Wei Huang from Nanjing Tech University, China demonstrates a simple thermal annealing approach to optimize the constitution of solution-processed mixed organic-cation lead iodide perovskite thin films for light-emitting diodes with external quantum efficiencies up to 8.6%. They find that the optimal constitution can be obtained by annealing at 100 degree Celsius for 10min when the dominant phase has high luminescence efficiency and homogeneous film morphology. It is fortunate that the optimal constitution of the mixed-cation halide perovskites can be easily obtained by thermal annealing, which opens up the possibility to produce high performance, large area and low cost perovskite light-emitting diodes.