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

Abstract

Efficient organic-inorganic metal halide perovskite absorbers have gained tremendous research interest in the past decade due to their super optoelectronic properties and defect tolerance. Lead (Pb) halide perovskites enable highly efficient perovskite solar cells (PSCs) with a record power conversion efficiency (PCE) of over 23%. However, the energy bandgaps of Pb halide perovskites are larger than the optimal bandgap for single junction solar cells, governed by the Shockley-Queisser (SQ) radiative limit. Mixed tin (Sn)-Pb halide perovskites have drawn significant attention, since their bandgap can be tuned to below 1.2 eV, which opens a door for fabricating all-perovskite tandem solar cells that can break the SQ radiative limit. This review summarizes the development of low-bandgap mixed Sn-Pb PSCs and their applications in all-perovskite tandem solar cells. Its aim is to facilitate the development of new approaches to achieve high efficiency low-bandgap single-junction mixed Sn-Pb PSCs and all-perovskite tandem solar cells.

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.…”

Realizing High Efficiency over 20% of Low‐Bandgap Pb–Sn‐Alloyed Perovskite Solar Cells by In Situ Reduction of Sn4+

“…Many efforts have been devoted to improving the PCE of low‐bandgap mixed Pb–Sn PSCs . However, it often exhibits a larger open‐circuit voltage ( V oc ) loss, and therefore, its efficiency is far behind that of pure Pb‐based PSCs with a medium bandgap.…”

“…[16,17] In addition to the tandem cell, the Sn-Pb-alloyed perovskite with a more suitable bandgap of %1.24 eV has a higher theoretical efficiency limit for a single-junction cell.Many efforts have been devoted to improving the PCE of low-bandgap mixed Pb-Sn PSCs. [18][19][20][21][22][23][24][25][26][27][28] However, it often exhibits a larger open-circuit voltage (V oc ) loss, and therefore, its efficiency is far behind that of pure Pb-based PSCs with a medium bandgap. It is worth to note that Yan and Zhu et al recently used guanidinium thiocyanate (GuaSCN) additive to passivate the grain boundaries and substantially reduce the defect density in mixed Pb-Sn perovskite films, leading to a high PCE over 20%, which is the first report for mixed Pb-Sn PSCs with PCEs over 20%.…”

Stabilization of Inorganic CsPb0.5Sn0.5I2Br Perovskite Compounds by Antioxidant Tea Polyphenol

“…For the Sn-based perovskite, the oxidation of Sn 2þ may generate Sn vacancies easily and leave along with the self P-type dopant which may serve as defect states to induce serious charge recombination. [38] Figure 2c,d shows the X-ray photoelectron spectroscopy (XPS) spectra of the Sn 3d bands of the CsPb 0.5 Sn 0.5 I 2 Br films without and with TP to quantify the surface compositions of CsPb 0.5 Sn 0.5 I 2 Br and study their chemical states. When the as-prepared CsPb 0.5 Sn 0.5 I 2 Br films were exposed to air for example during the preparation of the samples and the measurements, an oxidization could be easily found on the surface of the samples.…”