Identifying the Optimum Morphology in High‐Performance Perovskite Solar Cells

Li, Guijun; Ching, Kwong-Lung; Ho, Jacob Y L; Wong, Man; Kwok, Hoi Sing

doi:10.1002/aenm.201401775

Cited by 68 publications

(69 citation statements)

References 26 publications

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“…To confirm the reliability and accuracy of our results, we measured the J-V curves of the Mo-cathode cell at different scan directions and rates. Very small hysteresis between forward and reverse scans resulted in the average PCE of 12.88% and no deviations in J-V could be observed for different scan rates, as shown in Figure 3b and c. The smallhysteresis in dependence of the scan direction can be further reduced by controlling the crystallinity and morphology of the perovskite layer, as reported previously [9,[36][37][38]. …”

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confidence: 54%

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

et al. 2015

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supporting

confidence: 54%

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

et al. 2015

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“…According to previous report, [ 30 ] porous perovskite fi lm is detrimental to the performance of devices. Interestingly, in our work, it is found that the MAI concentration has a large impact on both the perovskite fi lms formation and photovoltaic performances of devices.…”

Section: Wileyonlinelibrarycommentioning

confidence: 90%

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Zhang

Mao

et al. 2015

Advanced Energy Materials

243

137

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to 20.1% [ 2,3 ] within fi ve years. The theoretical limit of the PVSC effi ciency has been estimated to be 31%, which is very close to the Shockley-Queisser limit (33%). [ 4 ] Perovskite deposition is crucial to produce high-effi ciency PVSCs. Generally, there are mainly three methods, including onestep solution spin-coating, vacuum vapor deposition, and two-step sequential deposition to prepare the hybrid perovskite fi lm. [5][6][7][8][9][10][11][12][13] Two-step sequential deposition has recently been reported, [ 7 ] which provides an effi cient and low-cost route to high-performance PVSCs.In a typical two-step sequential deposition of perovskites such as MAPbI 3 (MA = CH 3 NH 3 + ), PbI 2 is fi rst deposited on the substrate (mesoporous or planar scaffold) by spin-coating or vacuum evaporation, subsequently transformed into the perovskite (MAPbI 3 ) by exposing it to an anhydrous isopropanol (IPA) solution of MAI. For the two-step sequential deposition, the conversion and fi lm morphology of the fi nal perovskite fi lm strongly depend on the initial PbI 2 fi lm during the fi rst step of the process. [ 7,14,15 ] Conventionally, PbI 2 from dimethyl formamide (DMF) solution tends to form a layered and dense crystalline fi lm on a fl at substrate. However, the complete conversion of PbI 2 to perovskite on exposure to the MAI solution usually requires several hours. [ 7 ] However, this long reaction time in MAI solution could lead to the dissolution of perovskite fi lms. These drawbacks make it diffi cult to fabricate planar-structured PVSCs by sequential deposition method.Several strategies have been developed to solve this problem, including using elevated reaction temperature, [ 16,17 ] controlling the crystallization of PbI 2 by employing strong coordinative solvent of dimethyl sulfoxide [ 14 ] or using MAI vapor instead of MAI solution. [ 18 ] Recently, a cloudy PbI 2 fi lm prepared by gas-quenching treatment has been reported by Vak and co-workers, [ 19 ] which also enhances the conversion of PbI 2 to perovskites in the process of roll-to-roll fabrication. Zhao & Zhu [ 14 ] developed a new three-step sequential deposition process, where a unstable PbI 2 ·CH 3 NH 3 Cl precursor fi lm is fi rst deposited on the mesoporous TiO 2 substrate and followed by thermal decomposition to form PbI 2 fi lm; the PbI 2 fi lm The photovoltaic performance of perovskite solar cells (PVSCs) is extremely dependent on the morphology and crystallization of the perovskite fi lm, which is affected by the deposition method. In this work, a new approach is demonstrated for forming the PbI 2 nanostructure and the use of high CH 3 NH 3 I concentration which are adopted to form high-quality (smooth and PbI 2 residue-free) perovskite fi lm with better photovoltaic performances. On the one hand, self-assembled porous PbI 2 is formed by incorporating small amount of rationally chosen additives into the PbI 2 precursor solutions, which signifi cantly facilitate the conversion of perovskite without any PbI 2 residue. On the other hand, by...

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“…Except for the phase purity of perovskite, the morphology of perovskite is also quite important for the device performance. In general, perovskite film with a large grain size and smooth surface can improve the charge transport and reduce the charge recombination, which are favorable for the high PCE . So it is quite desirable to simultaneously manipulate the phase purity and morphology of perovskite film with the sequential deposition.…”

Section: Introductionmentioning

confidence: 99%

Iodine Induced PbI₂ Porous Morphology Manipulation for High‐Performance Planar Perovskite Solar Cells

et al. 2018

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The quality of the perovskite film has a vital influence on the performance of perovskite solar cells and it is quite desirable to simultaneously manipulate the crystallization and morphology of the perovskite film. In this study, conventional PbI2 is replaced with a PbI2/I2 mixed precursor during the first step of sequential deposition, causing the formation of a PbI2 porous nanostructure. By changing the content of I2 in the precursor, the morphology of the PbI2 film as well as the resulting perovskite film can be successfully modulated. With an optimal content of I2, a high‐quality perovskite film with a pure phase and smooth surface can be achieved. As a result, the conversion efficiency of perovskite solar cells using a PbI2/I2 mixed precursor can be as high as 18.63%, compared to 16.89% for the reference device through traditional sequential deposition with a pure PbI2 precursor.

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Identifying the Optimum Morphology in High‐Performance Perovskite Solar Cells

Cited by 68 publications

References 26 publications

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Iodine Induced PbI₂ Porous Morphology Manipulation for High‐Performance Planar Perovskite Solar Cells

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Identifying the Optimum Morphology in High‐Performance Perovskite Solar Cells

Cited by 68 publications

References 26 publications

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

Highly efficient perovskite solar cells based on mechanically durable molybdenum cathode

A Smooth CH3NH3PbI3 Film via a New Approach for Forming the PbI2 Nanostructure Together with Strategically High CH3NH3I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Iodine Induced PbI2 Porous Morphology Manipulation for High‐Performance Planar Perovskite Solar Cells

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A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Iodine Induced PbI₂ Porous Morphology Manipulation for High‐Performance Planar Perovskite Solar Cells