Reducing the Trap Density in MAPbI₃ Based Perovskite Solar Cells via Bromide Substitution

Abstract

The past decade has witnessed tremendous advancement in the field of halide perovskite (PSK) as a choice of material for high-performing solar cells fabrication. Here, we investigate the impact of the halide exchange through N-bromosuccinimide (NBS) treatment in MAPbI 3 based solar cells. We observed the partial halide exchange (I À to Br À ) or the filling of halide (X À ) vacancy upon treatment of different NBS concentrations experimentally by spectroscopic and diffractogram studies. We noted that halide exchange impacts the crystallization and is beneficial in improving the photovoltaic performance. The optimized 0.5 % NBS treated PSC exhibited a power conversion efficiency of 17.87 % due to an increment in open-circuit voltage (V oc ) and short circuit current (J sc ). We noted improved perovskite crystal growth upon Br À substitution; eventually, it helps to lower the trap density, reducing non-radiative recombination and renders the enhancement of long-term stability of PSC.

Fabrication of Highly Efficient and Ambient Stable Planar MAPbI3 Perovskite Solar Cells via Defect Passivation through Crosslinking Strategy

“…The calculated values for W & W/ o ‐TET PSCs, are 5.35 × 10 15 , and 7.77 × 10 15 cm −3 respectively and these values are similar to also similar to previously reported results. [ 48 ] We found that there is less N trap in the case of W‐TET passivated PSC compared to W/ o ‐TET devices. Thus, we believed that larger grain sizes in the perovskite layer in the case of TET passivation helped to reduce the trap state density.…”

Optimization of fluorinated interfacial layers with minimal surface coverage for hybrid perovskite materials

“…Numerous recent studies have revealed that the structure–activity relationship in perovskite surface passivating agents is not straightforward, 20 a ,22 and that the modification of the electronic properties or operational lifetime may result from effects that are specific to individual systems. 23 For example, when comparing the effect of 4-fluorophenethylammonium iodide (F-PEAI) 24 with its non-fluorinated analogue (PEAI), 8 a it was observed that F-PEAI-treated devices show enhanced stability when exposed to humidity. 24 This effect was assigned to the increased hydrophobicity of the fluorinated compound even though its fluorine content represents <15% w/w.…”