All‐inorganic Sn‐based Perovskite Solar Cells: Status, Challenges, and Perspectives

Abstract

Recently, the power conversion efficiency (PCE) of perovskite solar cells (PSC) based on organic‐inorganic hybrid Pb halide perovskites has reached 25.2 %. However, the toxicity of Pb has still been a main concern for the large‐scale commercialization of Pb‐based PSCs. Efforts have been made during the past few years to seek eco‐friendly Pb‐free perovskites, and it is a growing consensus that Sn is the best choice as Pb alternative over any other Pb‐free metal elements. Among Sn‐based perovskites, all‐inorganic cells are promising candidates for PSCs owing to their more suitable bandgap, better stability, and higher charge mobility compared to the organic‐inorganic hybrid counterparts. However, the poor phase stability of all‐inorganic Sn‐based perovskites (AISPs) and low PCE of their PSCs are most challenging in the field at present. Herein, recent developments on PSCs based on AISPs, including CsSnX3 and Cs2SnX6 (X=Br, I), are comprehensively reviewed. Primarily, the intrinsic characteristics of the two AISPs are overviewed, including crystallographic property, band structure, charge carrier property, and defect property. Sequentially, state‐of‐the‐art progress, regarding the photovoltaic application of AISPs as light absorber, is summarized. At last, current challenges and future opportunities of AISP‐based PSCs are also discussed.

Progress of Pb‐Sn Mixed Perovskites for Photovoltaics: A Review

“…[ 111 ] This result is in par with a recent theoretical study by Valadares et al., [ 112 ] on CsPb 1‐x Sn x I 3 perovskites where most mixed compositions showed bandgap under 1.2 eV with the lowest of 0.984 eV (for x = 0.8). Thus, the all‐inorganic Pb‐Sn mixed perovskites with I − as halide may qualify for absorbing higher wavelengths of the solar spectrum; however, their Pb‐only and Sn‐only counterparts have reported much lower efficiencies for CsPbI 3 (majority of reports with PCE ~15% with highest of 18%) [ 113 ] and CsSnI 3 (maximum PCE reported 5.03% despite the ideal bandgap of ~1.3 eV and theoretical PCE of 30%), [ 114 ] compared with their inorganic–organic mixed analogues. For CsPbX 3 , the problem lies in larger bandgaps and unfavorable band alignments, as well as phase stabilization issues with the small Cs + cation radius.…”

Environmentally Compatible Lead-Free Perovskite Solar Cells and Their Potential as Light Harvesters in Energy Storage Systems

“…However, for an actual application, for example, solar roofs, all-inorganic Sn-PSCs might be more applicable owing to their high device stability at the expense of low PCE. [ 61 ] Although many facets of Sn-PSCs need to be improved, we believe that Sn-PSCs have the potential to replace Pb-PSCs, considering their rate of development. We can expect researchers in the field Pb-free PSCs to come up with novel strategies [ 62 ] and adoption of new materials towards optimal energy alignments in Sn-PSCs [ 63 ] in near future.…”

Lead‐Free Cs2SnI6 Perovskites for Optoelectronic Applications: Recent Developments and Perspectives

“…Cs 2 SnI 6 perovskite exhibits an ambipolar nature, low‐optimized E g (1.26–1.62 eV), a high absorption coefficient (over 10 5 cm −1 ), and a high carrier mobility of 510 cm 2 V −1 s −1 . Although, few reviews on lead‐free perovskites have been published, [ 150–152 ] there have been no comprehensive reviews addressing the progress and development of Cs 2 SnI 6 for photovoltaic applications. Recently, the progress of CsSnI 3 and Cs 2 SnI 6 was systematically reviewed.…”

“…Recently, the progress of CsSnI 3 and Cs 2 SnI 6 was systematically reviewed. [ 150 ] However, we believe that a comprehensive review that is entirely focused on revealing the merits and demerits of double‐halide Cs 2 SnI 6 perovskite and its development is of paramount importance. Due to its ambient stability and nontoxicity, Cs 2 SnI 6 has received tremendous research attention.…”