A‐Site Cation Engineering of Metal Halide Perovskites: Version 3.0 of Efficient Tin‐Based Lead‐Free Perovskite Solar Cells

Abstract

Pb-based metal halide perovskites (MHPs) have emerged as efficient light absorbers in third-generation photovoltaic devices, and the latest certified power conversion efficiency (PCE) of Pb-based perovskite solar cells (PSCs) has reached 25.2%. Despite great progress, Pb-based MHPs are affected by toxicity, which hinders their market entry in a potential future large-scale commercialization effort. Therefore, the exploration of Pb-free MHPs has become one of the alternative solutions sought in the community. Among all the Pb-free MHPs, Sn-based MHPs show great promise owing to their similar or even superior theoretical optoelectronic characteristics. After several years of development, the PCE of Sn-based PSCs has recently been approaching 10%, with the breakthroughs mainly coming from A-site cation engineering of Sn-based MHPs. In this review, the crucial status of A-site cation engineering strategies in the research of Sn-based PSCs is highlighted. First, the way the features of A-site cation influence the structure and characteristics of MHPs is systematically demonstrated. Then, the state-of-the-art developments, focusing on A-site cation engineering of Sn-based MHPs, are comprehensively reviewed. Subsequently, the current challenges and opportunities for further boosting the performance of Sn-based PSCs are discussed. Finally, conclusions and perspectives on the promising Sn-based optoelectronic devices are discussed.

Variable dimensionality in ‘hollow’ hybrid tin iodide perovskites

“…To our surprise the reaction produced a novel structure type based on a 'hollow' B-site deficient perovskite, (TzH) 11 (H 3 PO 2 )Sn 6 I 23 (1). While the B-site deficient perovskite structure has been reported previously, 14,15 1 represents the first example of a layered variant of this family. On leaving the same reaction mixture for 2 months, a 3D 'hollow' perovskite (TzH) 3 Sn 2 I 7 (2) is the dominant product.…”

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

“…Although CsSnBr 3 possesses a stable cubic perovskite phase at room temperature, it is a wide band gap semiconductor with the main light absorption range of 350-700 nm. [88] CsSnI 3 with band gap of~1.3 eV (theoretical PCE over 30 %) [53,54] shows the greater potential as light absorber, but the highest PCE of reported PSCs based on CsSnI 3 is only 5.03 % up to now, [15] which is far below the theoretical limit. The main obstacles can be considered from three aspects: phase instability, poor film quality, and inferior interfaces of CsSnI 3 film.…”

“…Although all-inorganic PbÀ Sn alloying perovskites have been studied as the active layer of PSCs, where replacing 25 % Pb with Sn could improve the photovoltaic performance of PSCs with much improve phase stability and illumination stability, [52] AISPs-based PSCs are still worthy of in-depth study owing to their merits discussed above. However, the highest PCE of all-inorganic CsSnI 3 -based PSCs so far is only 5.03 %, [15] which is much lower than their theoretical limit over 30 %. [53,54] Promisingly, recent work has shown that PSCs based on all-inorganic CsGe 0.5 Sn 0.5 I 3 perovskite have reached PCE of 7.11 % with extremely attractive stability.…”

“…[94][95][96][97] Wang et al synthesized CsSnI 3 perovskite quantum dots (PVQDs) in a glove box using triphenyl phosphite (TPPi) as antioxidant solvent additive (ASA) by a simple one-pot method, and studied the photovoltaic performance of PSCs based on CsSnI 3 PVQDs as active layer. [15] The synthesis procedure of CsSnI 3 PVQDs is shown in Figure 8a, and it can be seen that the color of the solution with TPPi is reddish brown and becomes darker with the increase of TPPi concentration. After heat treatment, the color turns further black, which is similar to the solid state CsSnI 3 .…”

“…To seek for efficient Pb-free perovskites, researchers have studied Sn-based, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Ge-based, [29,30] Bi-based, [31][32][33][34] Sbbased, [31,32,35] and double metal-based perovskites. [31,[36][37][38] However, after several years' development, Pb-free PSCs still encountered with poor photovoltaic performance due to the intrinsic disadvantages of Pb-free perovskites.…”