Spontaneous enhancement of the stable power conversion efficiency in perovskite solar cells

Abstract

This work studies spontaneous enhancement in power conversion efficiency of multi-cation-halide perovskite solar cells which occurs days after device fabrication.

Triple-cation low-bandgap perovskite thin-films for high-efficiency four-terminal all-perovskite tandem solar cells

“…We relate this enhancement to the spontaneous enhancement phenomenon that has been previously reported for PSCs with various perovskite compositions and structures. [51][52][53][54] As portrayed in our previous work, 55 spontaneous enhancement in the PCE of PSCs is a general phenomenon and possibly occurs due to a reduction in straininduced trap states in the bulk of the perovskite materials, which happens gradually over time due to strain relaxation.…”

Ion migration drives self-passivation in perovskite solar cells and is enhanced by light soaking

“…It is interesting to note that grain growth has been observed by SEM, 6,19 but not with AFM. 7 Unlike AFM, SEM detects not only morphology, but chemical composition as well. 20 This may indicate that a compositional rather than a morphological transformation takes place.…”

“…Defects have been shown to be effectively passivated by additives, 4 light soaking 5 or even by storing under dark and dry conditions. [6][7][8] The latter pathway is of particular interest as there are no additional experimental steps or chemicals required. We have shown that the increase in device performance was accompanied by a spontaneous increase in average perovskite grain size, indicating that ions in the perovskite lm are very mobile, allowing the perovskite to self-heal as the ions move through the lattice.…”

“…6 It was shown that this ion migration can relax strain present in the perovskite lm, eliminating trap states. 7,8 Moghadamzadeh et al showed that aging-induced performance enhancement plays an important role in a wide range of lead halide perovskite materials and ruled out any inuence of the charge transporting materials. 7 Aging is facilitated by ion migration, which can occur spontaneously, but is greatly enhanced by voltage biasing 9 and light soaking.…”

“…7,8 Moghadamzadeh et al showed that aging-induced performance enhancement plays an important role in a wide range of lead halide perovskite materials and ruled out any inuence of the charge transporting materials. 7 Aging is facilitated by ion migration, which can occur spontaneously, but is greatly enhanced by voltage biasing 9 and light soaking. 10 In this study we investigate the inuence of the halide ratio on ion migration and track the morphological and optoelectronic properties of aging perovskite lms using SEM, XRD, photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and device performance.…”