Crystallization, Properties, and Challenges of Low‐Bandgap Sn–Pb Binary Perovskites

Abstract

Solution‐process and low‐temperature perovskites have motivated a broad range of interests and intensive studies for applications in solar cells (SCs) and photodetectors (PDs). Perovskite SCs with the bandgap of ≈1.5 eV currently exhibit the certified efficiency over 22% comparable with those of established thin film technologies. Meanwhile, perovskite PDs achieve superb performances in the visible region compared with commercial Si PDs. Partial substitution of Sn into Pb‐based perovskites can tune the absorption to near‐infrared (NIR) region, which would achieve an ideal‐bandgap perovskite approaching the Shockley–Queisser‐efficiency limit, low‐bandgap perovskite‐based bottom subcells in tandem devices (≈1.2 eV), and NIR photodetection. Here, various crystallization methods for growing low‐bandgap Sn–Pb binary perovskites are presented. Their impacts on morphology, crystallinity, preferred orientation, carrier lifetimes, Urbach energy, and stability of the resultant Sn–Pb binary perovskites are highlighted. Then, a description is given of single‐junction, 2‐terminal, and 4‐terminal SCs using these perovskites as absorbers, which achieve up‐to‐date efficiencies of 17.8%, 18.4%, and 21.2%, respectively. The current development of ultraviolet–visible–NIR PDs using these perovskites is also discussed. Furthermore, the challenges in controlling inter‐grain Sn/Pb element distributions and perovskite stability, which will influence performance and stability of Sn–Pb perovskite‐based devices, are presented. Finally, potential prospects are discussed for advancing low‐bandgap Sn–Pb binary perovskite‐based optoelectronic devices.

Low‐Bandgap Mixed Tin‐Lead Perovskites and Their Applications in All‐Perovskite Tandem Solar Cells

“…Moreover, the research efforts need to be devoted to the technical approaches and device designs that are adaptable to the industrial production, which are the prerequisites for the commercialization of this promising PV technology. Additionally, other optoelectronic applications of mixed Sn‐Pb perovskites, such as wide‐range and NIR photodetectors, LEDs, field effect transistors, and microlasers, are going to gain prosperous developments in the coming years. With all these progresses, mixed Sn‐Pb perovskites will demonstrate important applications in diverse optoelectronic technologies.…”

“…This makes the Pb mixed halide perovskites suitable candidates for the wide‐bandgap subcells in tandem solar cells. Meanwhile, the bandgap of mixed Sn‐Pb iodide perovskite absorbers can be tuned continuously from 1.6 to 1.2 eV, making them suitable absorbers for the low‐bandgap subcells in tandem solar cells. Wide‐bandgap Pb mixed halide perovskites have been combined with low‐bandgap inorganic absorbers such as Si and Cu 2 (In,Ga)Se 2 (CIGS) to fabricate efficient tandem solar cells .…”

Energy Level Tuning of PEDOT:PSS for High Performance Tin‐Lead Mixed Perovskite Solar Cells

“…The tunable bandgaps of perovskite open the opportunities for perovskite‐based tandem solar cells, the most promising approach to push the PCEs beyond the Shockley–Queisser limit for single‐junction solar cells . One prospective direction is to combine wide‐bandgap perovskite materials and low‐bandgap tin‐lead (Sn‐Pb) perovskite to fabricate all‐perovskite tandem solar cells .…”

“…[5] The tunable bandgaps of perovskite open the opportunities for perovskitebased tandem solar cells, the most promising approach to push the PCEs beyond the Shockley-Queisser limit for single-junction solar cells. [3,[10][11][12][13] One prospective direction is to combine wide-bandgap perovskite materials and low-bandgap tinlead (Sn-Pb) perovskite to fabricate allperovskite tandem solar cells. [4,14,15] The PCEs of 4-termianl all-perovskite solar cells have recently exceeded 23% with lowbandgap FA 0.6 MA 0.4 Sn 0.6 Pb 0.4 I 3 (FAMA) as bottom sub-cell.…”

Lead‐Free Tin‐Based Perovskite Solar Cells: Strategies Toward High Performance

“…B‐site metal cation substitution is quite common in Pb‐based PSCs, in which the Pb‐Sn based PSCs have come a long way toward single‐junction as well as tandem solar cells . Nevertheless, study on the substitution of Sn 2+ with other lead‐free metal ions is very few, probably because of the uncontrollable crystallization kinetics and defect physics.…”