Antioxidation and Energy-Level Alignment for Improving Efficiency and Stability of Hole Transport Layer-Free and Methylammonium-Free Tin–Lead Perovskite Solar Cells

Liu, Hui; Sun, Jiayun; Hu, Han; Li, Yan; Hu, Bihua; Xu, Baomin; Choy, Wallace C. H.

doi:10.1021/acsami.1c12180

Cited by 25 publications

(21 citation statements)

References 46 publications

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“…[59,[108][109][110] Liu et al, demonstrated a synergistic integration approach by uniting a reducing agent formamidine sulfonic acid (FSA) and in situ surface passivation together in Sn-Pb perovskites (FA 0.85 Cs 0.15 Sn 0.5 Pb 0.5 I 3 ) to enhance the performance of HTL-free and MA-free tin-lead mix PSCs, which exhibited a champion PCE of 17.4% with a bandgap of 1.27 eV. [111] This integration method appears to be more effective at preventing Sn 2+ oxidation and passivating the defect, resulting in a significantly lower trap density (1.65 × 10 15 for pristine and 1.08 × 1015 cm -3 for modified device), improved V TFL value (Figure 6d), better energy level alignment and enhanced charge carrier lifetime. Jesus et al have published a chemical engineering strategy based on adding dipropylammonium iodide (DipI) and sodium borohydride (NaBH 4 ) to prevent the early degradation of Snbased PSCs.…”

Section: Other Antioxidant/reductive Agentsmentioning

confidence: 99%

Section: Other Antioxidant/reductive Agentsmentioning

confidence: 99%

mentioning

confidence: 99%

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Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

Imran

Rauf

Raza

et al. 2022

Advanced Energy Materials

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its volatility and reversible/irreversible decomposition reaction even at low temperature, MA is gradually avoided in the material designs. [9] At the same time, FA is more thermally stable than MA due to its stronger hydrogen bonding with PbX 6 octahedra and benign reversible decomposition reaction below 85 °C, and it is the primary cation in practically all current high-performance PSCs. [10,11] Also, FA has no irreversible (nonselective) back reaction. [12] At the same time, in order to approach the bandgap of 1.34 eV according to the Schottky-Queisser (S-Q) limit, from initially MAPbI 3 to double cation (MAFA or FACs), [10,13,14] triple cation (CsMAFA) based perovskites, [5] eventually to quadruple (CsRbMAFA) based perovskites, [4,[15][16][17] and recently FAPbI 3 are dominated ones. [18][19][20] FAPbI 3 has an ideal, narrow bandgap since FA remains the largest organic cation that fits into a 3D perovskite crystal structure. [21] The implicit or explicit goal of perovskite research is to obtain a black FA-based (stable phase) perovskite at room temperature. Avoiding yellow phase impurities encouraged the advancement of processing techniques and elaborate multication, multi-halide mixtures.It has been proved that the invasion of Br anion at the X site is effective for stabilizing the black phase FA-based and other perovskites. But it leads to an adverse blue-shift of the bandgap disproportionately. For example, there is a spanning of 700 meV persisting in MAPbI x Br 1-x from 2.28 eV (MAPbBr 3 ) to 1.58 eV (MAPbI 3 ). [22] Furthermore, from a stability perspective, introducing Br anion in iodide-based perovskites is unfavorable since Br/I mixtures will undergo severe anion segregation Lead halide-based perovskite solar cells (PSCs) are intriguing candidates for photovoltaic technology because of their high efficiency, low cost, and simple process advantages. Owing to lead toxicity, PSCs based on partially/fully substituted Pb with tin have attracted tremendous attention, which would enable the ideal bandgap to approach the Shockley-Queisser (S-Q) limit. Especially, methylammonium (MA), bromide-free, tin-based perovskites are striking, because of the intrinsic poor stability of MA and blue shift caused by the incorporation of Br − . The first section of this review emphasizes the motivation for studying single-junction MA, Br-free, and Sn-based perovskites. The film quality improvement strategies of Sn-based perovskites, including additive, composition, dimensional, and interface engineering toward high-efficiency devices are comprehensively overviewed. Moreover, strategies to improve stability, where shelf, thermal and operational stabilities of the devices are summarized. Finally, this review concludes with a discussion of actual limitations and future prospects for Sn-based PSCs.

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Section: Other Antioxidant/reductive Agentsmentioning

confidence: 99%

Section: Other Antioxidant/reductive Agentsmentioning

confidence: 99%

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Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

Imran

Rauf

Raza

et al. 2022

Advanced Energy Materials

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“…To date, all-perovskite tandems with an efficiency over 24% have been reported . Compared to Pb 2+ , Sn 2+ exhibits different characteristics, including easy oxidation and crystallization of perovskite. − These features hamper the development of Sn-based PSCs with efficiency still lower than their Pb counterparts. Furthermore, most high-efficiency (>20%) Sn-Pb PSCs contain volatile methylammonium ions (MA + ) in perovskite composition and employ PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) as hole-transporting materials (HTMs), , yet both of them are detrimental to the stability of the resulting devices.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, most high-efficiency (>20%) Sn-Pb PSCs contain volatile methylammonium ions (MA + ) in perovskite composition and employ PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) as hole-transporting materials (HTMs), , yet both of them are detrimental to the stability of the resulting devices. Especially, PEDOT:PSS exhibits strong acidity, hygroscopic nature, and shallow HOMO (highest occupied molecular orbital) value, , greatly limiting its scalable application in tandems.…”

Section: Introductionmentioning

confidence: 99%

Efficient and Stable Methylammonium-Free Tin-Lead Perovskite Solar Cells with Hexaazatrinaphthylene-Based Hole-Transporting Materials

Guo

Zhang

Liu

et al. 2022

ACS Appl. Mater. Interfaces

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Incorporating non-aqueous hole-transporting materials (HTMs) to replace the widely used PEDOT:PSS is favorable for improving the stability of tin-lead perovskite solar cells (Sn-Pb PSCs). Herein, hexaazatrinaphthylene (HATNA) is found to be a promising HTM building block for Sn-Pb PSCs. By introducing triphenylamine (TPA) and methoxy-triphenylamine into the HATNA core, molecular energy levels and surface wettability can be well regulated, and a high hole mobility and thermal stability can be maintained. Moreover, a homogeneous Sn-Pb perovskite film with low Sn4+ contents and vertically orientated grains can be prepared on the substrate TPA-HATNA. Compared with PEDOT:PSS, the optimal TPA-HATNA-based methylammonium-free device enables a 70 mV increase in V OC, delivering a remarkable PCE exceeding 18% (certified 16.4%). Impressively, the TPA-HATNA-based devices without encapsulation retain 90% efficiency after aging for 600 min under maximum-power-point tracking. Our work provides alternative HTMs for boosting the performance of Sn-Pb PSCs.

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Rubidium Iodide Reduces Recombination Losses in Methylammonium‐Free Tin‐Lead Perovskite Solar Cells

Yang

MacQueen

Menzel

et al. 2023

Advanced Energy Materials

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The tunable bandgap energy (E g ) of metal halide perovskites has led to one of the most interesting developments in this context, namely the all-perovskite tandem solar cells (APTSCs), which is formed by combining two perovskite-based sub-cells with different bandgaps into a monolithically stacked structure. This tandem structure allows the solar cell to absorb different components of sunlight within the two absorber layers, extracting on average more useable energy per photon absorbed. Consequently, tandem solar cells can achieve a power conversion efficiency (PCE) above that of a single-junction solar cell, the limiting efficiency of which is marked by the single-junction radiative limit. [2] To most effectively implement this concept, the monolithic APTSCs usually consist of a narrow (≈1.20 eV) and a wide (≈1.80 eV) E g perovskite for the bottom and top subcells, [3] respectively. APTSCs have been reported with PCEs of 28.0%, i.e., well beyond 25.7% PCE of the current record single-junction perovskite solar cell (PSC). [4,5] This study concerns the bottom cell of APTSCs, which uses a narrow bandgap perovskite film as the light absorber. Mixing tin (Sn) and lead (Pb) as the B-site cation is required to achieve a sufficiently small E g . [6] Sn-Pb perovskites reach a minimum E g of ≈1.20 eV when the ratio of Sn to Pb is about Outstanding optoelectronic properties of mixed tin-lead perovskites are the cornerstone for the development of high-efficiency all-perovskite tandems. However, recombination losses in Sn-Pb perovskites still limit the performance of these perovskites, necessitating more fundamental research. Here, rubidium iodide is employed as an additive for methylammonium-free Sn-Pb perovskites. It is first investigated the effect of the RbI additive on the perovskite composition, crystal structure, and element distribution. Quasi-Fermi level splitting and transient photoluminescence measurements reveal that the RbI additive reduces recombination losses and increases carrier lifetime of the perovskite films. This finding is attributed to an approximately ten-fold reduction in the defect density following RbI treatment, as probed using constant final state yield photoelectron spectroscopy. Additionally, the concentration of Sn vacancies is also reduced, and the perovskite film becomes less p-type both in the bulk and at the interface towards the electron contact. Thus, the conductivity for electrons increases, improving carrier extraction. As a result, the open-circuit voltage of RbI-containing solar cells improves by 61 mV on average, with the best efficiency >20%. This comprehensive study demonstrates that RbI is effective at reducing recombination losses and carrier trapping, paving way for a new approach to Sn-Pb perovskite solar cell research.

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Antioxidation and Energy-Level Alignment for Improving Efficiency and Stability of Hole Transport Layer-Free and Methylammonium-Free Tin–Lead Perovskite Solar Cells

Cited by 25 publications

References 46 publications

Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

Efficient and Stable Methylammonium-Free Tin-Lead Perovskite Solar Cells with Hexaazatrinaphthylene-Based Hole-Transporting Materials

Rubidium Iodide Reduces Recombination Losses in Methylammonium‐Free Tin‐Lead Perovskite Solar Cells

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