Debei Liu

Efficient perovskite solar cell fabricated in ambient air using one-step spin-coating

One-step spin coating is a simple method which has been widely used in fabricating perovskite solar cells. However, this method was vastly demonstrated in glove box wherein the influence of moisture is negligible. Thus the use of one-step spin-coating in ambient air has not been comprehensively investigated. In this work, we employ one-step spin-coating method to coat perovskite films in ambient air (with humidity above 50%), and then the perovskite films are annealed in vacuum or air. Experimental results show that by using vacuum annealing, a power conversion efficiency of 12.98% is attained, and this is 45% higher than that attained by air annealing method. This improvement is mainly attributed to the fast solvent evaporation process in vacuum during annealing, which induces high supersaturation that leads to higher coverage of perovskite film.

The interface degradation of planar organic–inorganic perovskite solar cell traced by light beam induced current (LBIC)

The light beam induced current (LBIC) method was adopted to nondestructively map the photoresponse of real planar organic–inorganic hybrid perovskite solar cells (PSCs). It is found that the photoresponse of the devices is not uniform even though the morphology of the perovskite films from scanning electron microscope (SEM) or atomic force microscope (AFM) images shows uniform character. This nonuniformity of the photoresponse of the devices is further exacerbated after degradation, which can be well traced by the LBIC method. The indistinguishable morphology change during the device degradation indicates that the degradation of the device is not mainly determined by the morphology of the perovskite layer, but by the interface between the perovskite and the electrode. By using the LBIC method, the worse performing area of the device is identified and then removed accordingly. The current density of the device can be enhanced from 19.44 mA cm−2 to 21.72 mA cm−2 after this clearance of the worse performing area.

Interfacial engineering with ultrathin poly (9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) layer for high efficient perovskite light-emitting diodes

Organic-inorganic hybrid perovskites have attracted great attention in the field of lighting and display due to their very high color purity and low-cost solution-process. Researchers have done a lot of work in realizing high performance electroluminescent devices. However, the current efficiency (CE) of methyl-ammonium lead halide perovskite light-emitting diodes (PeLEDs) still needs to be improved. Herein, we demonstrate the enhanced performance of PeLEDs through introducing an ultrathin poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) buffer layer between poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and CH3NH3PbBr3 perovskite. Compared to the reference device without PFO, the optimal device luminous intensity, the maximum CE, and the maximum external quantum efficiency increases from 8139 cd m-2 to 30 150 cd m-2, from 7.20 cd A-1 (at 6.8 V) to 10.05 cd A-1 (at 6.6 V), and from 1.73% to 2.44%, respectively. The ultrathin PFO layer not only reduces the exciton quenching at the interface between the hole-transport layer and emission layer, but also passivates the shallow-trap ensure increasing hole injection, as well as increases the coverage of perovskite film.