Acquiring High‐Performance and Stable Mixed‐Dimensional Perovskite Solar Cells by Using a Transition‐Metal‐Substituted Pb Precursor

Abstract

In recent years, as the most promising photovoltaic technology, lead halide perovskite solar cells (PSCs) have become a research hotspot owing to their super-high power conversion efficiency (PCE) and simple preparation method. However, the toxicity of lead and instability under high humidity and temperature greatly affects their further development. In this study, we investigated three kinds of non-toxic transition metal cations (Zn , Mn , and Ni ) at 3 % to partially substitute lead cations and form mixed-dimensional (MD) perovskites. Among these transition metals, Zn is the most suitable to replace Pb and Zn-MD perovskite device exhibits the best PCE of 18.35 %. In addition, we further studied the humidity and heat stability of methylammonium lead iodide (MA), Zn-MD, Mn-MD, and Ni-MD perovskite devices. Upon exposure to about 50 % relativity humidity (RH) for 800 h, the MA and three MD devices, respectively, maintain 30 %, 81 %, 80 %, and 74 % of their original PCE. After aging at 60 °C for 100 h, the PCEs of the four PSCs retain 40 %, 84 %, 85 %, and 76 % of their starting values, respectively. The results show that the three MD perovskite devices have high humidity and heat stability and using transition-metal-substituted Pb can gain long-term stability and reduced toxicity of PSCs.

A Review of Perovskites Solar Cell Stability

“…[57a] This was due to the low carrier mobility on the vertical direction caused by these insulating large organic cation layer supposedly parallel to the electrodes . Dai and co‐workers fabricated three MD perovskites by nontoxic transition metal cations (Zn 2 + , Mn 2 + , and Ni 2 + ) at 3% to partially replace lead cations in MAPbI 3 . The MD devices could, respectively, retain 81%, 80%, and 74% of their original PCE values under about 50% RH for 800 h. The PCE of MD perovskite devices maintained 84%, 85%, and 76% of their starting values at 60 °C for 100 h .…”

“…Dai and co‐workers fabricated three MD perovskites by nontoxic transition metal cations (Zn 2 + , Mn 2 + , and Ni 2 + ) at 3% to partially replace lead cations in MAPbI 3 . The MD devices could, respectively, retain 81%, 80%, and 74% of their original PCE values under about 50% RH for 800 h. The PCE of MD perovskite devices maintained 84%, 85%, and 76% of their starting values at 60 °C for 100 h . Leyden et al demonstrated that solar cells fabricated with FAPbI 3 as active layer had better thermal stability than those of MAPbI 3 .…”

Perovskite Thin Film Materials Stabilized and Enhanced by Zinc(II) Doping

“…Power conversion efficiencies up to 20.06% [23] (with 1% of Zn(II) content) and enhancement factors of 1.07 to 1.33 (when comparing undoped and doped devices) are the trend. A PCE of 18.2% was reported by using 3% of ZnCl 2 in 2017 [11] and 18.35% in 2018 [14] with 3% ZnI 2 . A similar value (PCE = 18.25%) was found for 5% Zn(II) [15].…”

“…This finding is a second strong indication that Zn dopants are incorporated in the perovskite lattice. Dai et al came forward with a thorough work [14] on the doping of Pb perovskite with 3% of the transition metals Zn 2+ , Mn 2+ and Ni 2+ . The resulting materials were mixed dimensional perovskite films (MA(Pb:M)I 3 ) with a higher stability and in the case of the Zn 2+ (from ZnI 2 ), a superior photovoltaic performance of 18.35% (PCE, power conversion efficiency) (a 30% increase relative to undoped devices).…”

“…It was soon discovered that lead could partially be replaced by Co 2+, Zn 2+ , Mg 2+ , Mn 2+ , Ni 2+ due to their similar atomic radii and divalent nature [9], also in perovskite nanocrystals [10]. Not long after this, several extensive studies focused on doping with Zn 2+ commenced [11][12][13][14][15][16]. Zinc is particularly interesting due to its non-toxic nature, its inability to oxidize or reduce easily, and its abundance on Earth.…”