Bication lead iodide 2D perovskite component to stabilize inorganic α-CsPbI
            <sub>3</sub>
            perovskite phase for high-efficiency solar cells

Materials Research Letters

Lin

Lee

et al. 2018

118

Organic-inorganic metal halide hybrids have emerged as new generation functional materials with exceptional structure and property tunability for a variety of applications. Besides the most investigated ABX 3 metal halide perovskites, a variety of hybrids consisting of a wide range of organic cations and metal halide anions have been developed and studied recently. Here, we provide an overview of these new materials possessing various crystallographic structures, including double perovskites, low dimensional hybrids, and other perovskite-related materials. We discuss their syntheses, functional properties, and optoelectronic applications. Challenges and opportunities are then laid out for these hybrid materials beyond perovskites. IMPACT STATEMENTBy choosing appropriate organic cations and metal halide anions, single crystalline ionically bonded hybrid materials can be assembled to possess various structures beyond the well-known ABX 3 perovskite. These hybrid materials exhibit exciting new properties with potential applications in a variety of areas. ARTICLE HISTORY

Section: Corrugated-2d Organic Metal Halide Hybridsmentioning

confidence: 99%

Organic–inorganic metal halide hybrids beyond perovskites

Materials Research Letters

Lin

Lee

et al. 2018

118

“…[17] Meanwhile, the past decade has witnessed unprecedented success of organicinorganic hybrid perovskites in PV applications, with the reported PCE of perovskite solar cells exceeding 23%. [29][30][31][32][33][34][35][36][37][38] Among these all-inorganic perovskite materials, α-CsPbI 3 exhibits an ideal optical bandgap (E g ) of 1.73 eV for PV applications. [29][30][31][32][33][34][35][36][37][38] Among these all-inorganic perovskite materials, α-CsPbI 3 exhibits an ideal optical bandgap (E g ) of 1.73 eV for PV applications.…”

mentioning

confidence: 99%

14.1% CsPbI₃ Perovskite Quantum Dot Solar Cells via Cesium Cation Passivation

Ling

Advanced Energy Materials

Yuan

et al. 2019

301

284

During the past decade, inorganic CQDs, namely the lead chalcogenides (e.g., PbS), have attracted tremendous attention in solution-processed solar cells. Due to the great efforts on CQDs synthesis modification, [7][8][9] surface passivation, [10][11][12] and device fabrication optimization, [13][14][15][16] PbS QD solar cells continue to progress at an extraordinary rate, improving overall efficiencies by ≈1% per year and currently have a certified power conversion efficiency (PCE) exceeding 12%. [17] Meanwhile, the past decade has witnessed unprecedented success of organicinorganic hybrid perovskites in PV applications, with the reported PCE of perovskite solar cells exceeding 23%. [18][19][20][21][22][23][24][25][26][27][28] However, the challenging stability issues of these hybrid perovskites further motivate the research of all-inorganic perovskites (CsPbX 3 , X = Cl − , Br − , I − or mixed halides) without any volatile organic components. [29][30][31][32][33][34][35][36][37][38] Among these all-inorganic perovskite materials, α-CsPbI 3 exhibits an ideal optical bandgap (E g ) of 1.73 eV for PV applications. However, the nonphotoactive orthorhombic phase (E g = 2.82 eV) is more thermodynamically preferred at low temperature. [29] Therefore, the perovskite phase of CsPbI 3 usually requires complex annealing processes at high temperature to achieve satisfactory film quality. As mentioned above, QD technology offers colloidal synthesis of conventional bulk materials, which Surface manipulation of quantum dots (QDs) has been extensively reported to be crucial to their performance when applied into optoelectronic devices, especially for photovoltaic devices. In this work, an efficient surface passivation method for emerging CsPbI 3 perovskite QDs using a variety of inorganic cesium salts (cesium acetate (CsAc), cesium idodide (CsI), cesium carbonate (Cs 2 CO 3 ), and cesium nitrate (CsNO 3 )) is reported. The Cs-salts post-treatment can not only fill the vacancy at the CsPbI 3 perovskite surface but also improve electron coupling between CsPbI 3 QDs. As a result, the free carrier lifetime, diffusion length, and mobility of QD film are simultaneously improved, which are beneficial for fabricating high-quality conductive QD films for efficient solar cell devices. After optimizing the post-treatment process, the short-circuit current density and fill factor are significantly enhanced, delivering an impressive efficiency of 14.10% for CsPbI 3 QD solar cells. In addition, the Cs-salt-treated CsPbI 3 QD devices exhibit improved stability against moisture due to the improved surface environment of these QDs. These findings will provide insight into the design of high-performance and low-trap-states perovskite QD films with desirable optoelectronic properties. Perovskite Quantum DotsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.Solution-processed colloidal quantum dots (CQDs) are promising candidates for the next generation photovoltaics (PVs) due to the excellent tuna...

“…[47] Recently, Ma and co-workers pointed that Yb doping can reduce the number of defects and trap states, and obtained high PCE of 14.1%. [52] Zhao and co-workers employed ethylenediamine cations (EDA 2+ ) as 2D barrier molecule into α-CsPbI 3 and achieved a PCE of 11.8% with excellent thermal stability; [53] Huang and co-workers found that mixing a small amount of sulfobetaine zwitterions in α-CsPbI 3 could stabilize the phase and obtained PCE of 11.4%; [54] These results indicate quasi-2D structure could achieve efficient and stable CsPbI 3 PSCs in the future, but their PCE should be further enhanced. Finally, a PCE of 13.4% is achieved.…”

mentioning

confidence: 99%

Ruddlesden–Popper 2D Component to Stabilize γ‐CsPbI₃ Perovskite Phase for Stable and Efficient Photovoltaics

Wang

Advanced Energy Materials

et al. 2019

122

111

The highest certified power conversion efficiency (PCE) of black phase based CsPbI3 perovskite solar cells has exceeded 18%, and become a hotspot in recent progress. However, the black phase of CsPbI3 rapidly transforms to yellow phase in ambient conditions due to its thermodynamic instability. Here, a Ruddlesden–Popper 2D structure is introduced into γ‐CsPbI3 film to stabilize the black phase via reducing dimensionality. It is found that a judicious amount of phenylethylammonium iodide can adjust the dimensionality of γ‐CsPbI3 film from 2D to quasi‐2D and 3D phase. Comprehensive consideration to obtain both the stability and high PCE, quasi‐2D (n = 40) γ‐CsPbI3 delivers a reproducible PCE of 13.65% with negligible hysteresis. By utilizing femtosecond transient absorption and time‐resolved PL decay, similar carrier kinetics in n = 40 and ∞ samples are observed, meaning an efficient charge extraction. More importantly, when the device is placed at 80 °C in N2 condition or in air with RH of 25–30%, its PCE keeps ≈88% and ≈89% of its initial PCE after 12 days, respectively. Such results are better than the 3D one (≈69% and ≈16%, respectively).