High-efficiency and stable perovskite solar cells prepared using

Subscriber access provided by Nottingham Trent University

Energy, Environmental, and Catalysis Applications

High-efficiency and stable perovskite solar cells prepared using chlorobenzene/acetonitrile anti-solvent Huayang Li, Yiqiu Xia, Chen Wang, Ge Wang, Yi Chen, Liuxing Guo, Dongxu Luo, and Shanpeng Wen ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.9b12323 • Publication Date (Web): 05 Sep 2019 Downloaded from pubs.acs.org on September 5, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

High-Efficiency and Stable Perovskite Solar Cells Prepared Using Chlorobenzene/Acetonitrile Anti-Solvent Huayang Li, † Yiqiu Xia, † Chen Wang, † Ge Wang, † Yi Chen, † Liuxing Guo, † Dongxu Luo, † Shanpeng Wen, *,†

†State

Key Laboratory on Integrated Optoelectronics and college of Electronic

Science & Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China

Email: [email protected]

1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 28

Abstract: Preparing high-quality perovskite film with large grain size and less trap states is of vital importance in boosting the efficiency and stability of perovskite solar cells (PSCs). However, it’s still difficult to obtain perfect MAPbI3 films by antisolvent treatment so far because of the small grain size, pinholes and numerous defects in perovskite layers. Herein, the acetonitrile (ACN) was introduced into the chlorobenzene (CB) anti-solvent to modify the MAPbI3 active layer. The results show that the ACN could control the ratio of the DMSO in MAI-PbI2-DMSO intermediate phase film effectively and thus manipulate the formation of MAPbI3 film. Relatively high-quality perovskite films with larger grain size were obtained when we adding 6% v/v ACN into CB anti-solvent. Based on the ACN-modified MAPbI3 film, the n-i-p planar device with the structure of FTO/SnO2/MAPbI3/spiro-OMeTAD/Ag yields the best power conversion efficiency (PCE) of 18.9%. It exhibited an enhancement of 16.6% in efficiency compared with the PCE of 16.2% for the control device. In addition, the device based on ACN-modified MAPbI3 also presents improved stability in air atmosphere.

Key words: perfect MAPbI3 films, antisolvent treat, reduced defects, improved stability, perovskite solar cells


Page 3 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Because of the low cost, facile fabrication process and great progress in efficiency of the organic-metal halides perovskite solar cells (PSCs), they are obtaining worldwide attention in the last few years.1-6 The unique opto-electronic properties of these perovskite absorbers, including high tolerance of defects, controllable band-gap, long exciton diffusion length, are considered to be the main reason for the impressive improvement in the performance.7-11 After numerous fundamental researches and modification for PSCs from multiple aspects, the recorded PCE of 24.2% for PSCs has been realized.12 which made the PSCs one of the most promising photovoltaic technologies. Unfortunately, the perovskite active layers are always fabricated with solution process and the obtained films are typically polycrystalline, which results in the formation of grain boundaries (GBs). It has been demonstrated that the defects mainly generate at the GBs or on the surface of the of perovskite film because crystallization terminate.13-15 These defects will capture electrons or holes and lead to enhanced nonradiative recombination rate, curtailing carrier lifetime and device performance.16 Meanwhile, the GBs have been reported to act as the major channel of the ion migration. Lots of vacancies will be left after ion migration, which has been suggested to be an important factor contributing the J-V hysteresis in device.17-18 Plenty of GBs also provide pathway for moisture or the oxygen ingress and accelerate the film degradation.14, 19, 20 Therefore, obtaining high quality perovskite film with less GBs and defects has been recognized as one critical challenge to realize superior efficiency and stable PSCs. To this end, many successful strategies have been developed such as interfacial treatment,21-23

surface

or

grain

boundaries

passivation24-26

and

perovskite



Page 4 of 28

crystallization control.27-30 Among these strategies, adjusting the dynamic in crystallization process of the perovskite film is one of the most straightforward methods to prepare high-quality perovskite film, which typically call for rapid homogeneous nucleation and slow crystal growth. The anti-solvent engineering approach (also called one-step method) relying on the use of dimethylformamide (DMF) and dimethylsulphoxide (DMSO) mixture solvents provides slow nucleation of seeds, thus is widely used to obtain dense and high crystalline perovskite thin film.31 In this process, the amount of residual DMSO in the intermediate film is a dominant factor on the final quality of perovskite, but meanwhile difficult to control which highly related to the DMF:DMSO ratio in the perovskite precursor solution as well as anti-solvent used. Less DMSO residues it may be hard to induce well-defined intermediate phase for reproducible and uniform growth of MAPbI3. While excessive amount of DMSO in the perovskite intermediate phase would lead to an inhomogeneous perovskite film because of the gradual vaporization of DMSO from the perovskite film.32 Keeping this in mind, it is important and necessary to develop a simple, convenient and reproducible method that can make rational DMSO residues in the perovskite intermediate phase more controllable. In this paper, we added the ACN as additive into the chlorobenzene antisolvent to wash the MAPbI3 film, and found that the ACN play an important role in the perovskite crystallization process. The introduced ACN could effectively rationalized the ratio of DMSO in the intermediate phase, leading to the formation of dense and uniform MAPbI3 with larger grain size and lower defect density. Consequently, the device based on the modified MAPbI3 prepared with ACN/CB mixed antisolvent shows the highest PCE of 18.9% with less hysteresis in comparison with that (16.2%) for the control device. In addition, the air stability of the modified devices was


Page 5 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


enhanced obviously due to the improved perovskite film, which could still maintain the 80% of the initial efficiency for 17 days in ambient atmosphere with humidity of 20%. This work provides a facile method to prepare high-quality perovskite film, which is beneficial for the further improvement in device performance. RESULTS AND DISCUSSION Figure 1a shows the final device with the structure of FTO/SnO2/MAPbI3/SpiroOMeTAD/Ag. The MAPbI3 active layer prepared with CB/ACN antisolvent was sandwiched between the SnO2 and Spiro-OMeTAD, which can accept and transport the electrons and holes, respectively. Figure 1b shows the cross-section SEM images of the final devices. The corresponding thickness for SnO2, MAPbI3 and SpiroOMeTAD layer is 23 nm, 390 nm and 160 nm, respectively. Figure 1c exhibits the schematic diagram of the fabrication process of the MAPbI3 film. The perovskite precursors were spin-coated on the FTO/SnO2 substrates and mixed anti-solvent with different CB/ACN volume ratio (1:0, 1:0.02, 1:0.04, 1:0.06, 1:0.08, 1:0.12) were used to quench the wet film and rapidly form intermediate seed layer. At this stage we observed pronounced color difference, brown-like-colored rather than colorless after adding ACN into the anti-solvent. This has been identified as a satisfactory film condition by Saliba et al.[33] The intermediate films were finally annealed at 100 oC for 10 min to complete the subsequent perovskite crystallization step.



Page 6 of 28

Figure 1. (a) The structure of the final device, (b) the cross-section SEM images of the device treated with CB/ACN (6%), (c) the schematic diagram of the fabrication process for the MAPbI3 film. Figure 2 shows the scan electron microscopy (SEM) images of MAPbI3 films when adding different volume of ACN into the anti-solvent. It can be seen that all samples show full surface coverage though, the control perovskite film using CB anti-solvent presents small grain size and plenty of grain boundaries. It’s interesting to find that the ACN additive in CB anti-solvent can tune the grain size significantly. The average grain sizes increases gradually from 220.4 nm to 407.7 nm as ACN volume ratio increase from 0 to 6%. Further increasing the volume ratio of ACN, the grain size becomes non-uniform and begins to decrease gradually (shown in Figure S1). These morphology evolutions indicated that ACN can effectively manipulate the growth of the perovskite crystals. Possible reasons we believed are related to the amount of residual DMSO in the intermediate film that will be discussed later.


Page 7 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. The SEM images of the MAPbI3 deposited on the FTO/SnO2 with different volume rations of CB:ACN. The XRD measurement was also carried out to investigate how the perovskite crystallinity will be affected by ACN additive. Figure 3a shows the XRD patterns of the CH3NH3PbI3 films deposited on glass/SnO2 substrates. It can be seen that all the perovskite films show the similar XRD patterns, peaks at 14.1o, 28.4o and 31.9o correspond to the (110), (220) and (310) planes respectively. This indicated no phase change caused by introducing ACN. It is noticed that the perovskite film mediated by 6% ACN (in anti-solvent) showed maximum peak intensity as well as lowest full width at half maxima (FWHM) value of (110) (see Figure S3 for more details). Taken together, SEM and XRD results suggested the best crystallization quality of perovskite under 6% ACN condition. To understand the positive role of ACN in the formation of the perovskite film, the Fourier Transform infrared spectrometer (FTIR) was employed. Figure 3b shows the FTIR spectra of the intermediate perovskite films quenched by different CB:ACN anti-solvents. The vibration peaks at 3193 cm-1 and 1019 cm-1 can be attributed to the N-H and S=O stretching vibration, respectively.34, 35 These two peaks belong to perovskite and DMSO component that can be used to 7 ACS Paragon Plus Environment


Page 8 of 28

evaluate the residual level of DMSO in the film. We calculated the ration of the peak intensity of the S=O at 1019 cm-1 and N-H at 3193 cm-1, the ration decreases from 2.53 to 1.61 on increasing the ACN ratio in CB (see in Figure S4), suggesting there’s less DMSO left. The result implied that the ACN can extra excess DMSO from perovskite intermediate film effectively. This is conductive to the reduction of voids and small-size grain caused by gradual vaporization of DMSO. Meanwhile, the reduced perovskite quality at high ACN dose (less DMSO residual) probably due to more MAPbI3 crystal nucleus formed in this case, which is also difficult to grow into large-grain size perovskite film. By tuning the volume ratio of ACN, it can provide a valid method to control the residual DMSO in perovskite intermediate phase so as to produce dense and uniform MAPbI3 with larger grain size. The modified MAPbI3 films by using CB:ACN anti-solvent showed higher absorption intensity than the control perovskite film from the onset to 550 nm (see in Figure S5), this can be ascribed to the improved perovskite crystallinity.

Figure 3. (a) The XRD patterns of the MAPbI3 films deposited on glass/SnO2 substrates prepared with different ratio of ACN additive. (b) The FT-IR spectra of the MAPbI3 films on KBr substrate prepared with different ratio of ACN additive without annealing. 8 ACS Paragon Plus Environment

Page 9 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


We fabricated the planar heterojunction devices with the construction of FTO/SnO2/MAPbI3/Spiro-OMeTAD/Ag to estimate the effects of ACN additive on the final device performance. Figure 4a shows the J-V curves of these corresponding devices, and Table S1 gives the detailed photovoltage parameters. It clearly exhibits that the device prepared with no ACN shows the poorest performance with the PCE of 16.2% due to the low short-circuit current density (Jsc=21.2 mA cm-2), open-circuit voltage (Voc=1.09 V) and fill factor (FF=0.7). Upon introducing ACN additives into anti-solvent, all the devices show enhanced PCE. As expected, the best PCE of 18.9% was obtained when ACN ration was at 6% with the short circuit current (Jsc) of 22.3 mA cm-2, Voc of 1.13 V and FF of 0.75. The J-V curves for the optimized and control devices with both forward and reverse scan directions are presented in Figure 4b. Table 1 shows the detailed performance parameters of the corresponding devices. ACN additive in anti-solvent not only increased the efficiency but also suppressed the anomalous device hysteresis. The control device exhibits a better PCE of 16.2% in reverse scan and 13.7% in forward scan, the hysteresis index was calculated to be 0.15. By contrast, the ACN optimized device presents smaller hysteresis index of 0.09 with the PCE of 18.9% (in reverse scan) and 17.2% (in forward scan).36 In addition, the J-V curves for the device measured under different delay time (see Figure S6) also indicated that the device prepared with CB/ACN antisolvent had less hysteresis. It has been reported

that the hysteresis in the perovskite solar cell is mainly caused by the carrier recombination and the ion migration in the perovskite film.17,

22

Therefore, the

reduced hysteresis implies the reduced recombination loss and suppressed ion migration which is in accordance with less grain boundaries and improved perovskite crystal quality after ACN modification. The Figure 4c shows the external quantum efficiency (EQE) of the devices prepared without and with 6% ACN additive. It can



Page 10 of 28

be observed that the device with 6% ACN shows an enhanced EQE along the whole wavelength from the 300 to 800 nm. The calculated current density for the device without and with 6% ACN additive is 20.3 and 21.2 mA cm-2, respectively, which is basically consistent with measured Jscs from the practical J-V tests. To evaluate the real PCE of the corresponding devices, the steady-state power output under the applied bias at the maximum power point was measured. As shown in Figure 4d, the current density for the device with 6% ACN additive increase to 19.8 mA cm-2 in 20 s with the stabilized efficiency of 18.02%. The Jsc for control device shows a slow rise to the maximum photocurrent density of 17.97 mA cm-2 within 60 s, leading to a final stabilized PCE of 15.27%. Rapidly reaching steady-state power output upon using ACN also suggested that the unsatisfactory ion migration is effectively suppressed. Figure 4e shows the statistical device efficiency w/o or with ACN modification. It shows that the devices with 6% ACN have higher and more concentrated PCE distribution, representing an improved reproducibility. Finally, the stability of the two devices was also investigated without encapsulation under ambient atmosphere (20% RH, room temperature). As can be seen in Figure 4f, the PCE for the control device degrades to 59% of its initial value after 11 days. However, the device prepared with 6% ACN become more stable, it still maintains the 80% of the initial PCE after 17 days.


Page 11 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. (a) J-V curves of devices prepared with different antisolvents, (b) J-V curves of the control and optimized device measured at forward and reverse scan, (c) the EQE of the control and optimized device, (d) the photocurrent versus the time measured at the maximum power point voltage (0.85 V for control device and 0.91 V for the optimized device), (e) the statistics of the PCE of the control and optimized device, (f) the stability of the corresponding devices stored in ambient air with humid of 20%.



Page 12 of 28

Table 1. The photovoltaic parameters of the control and optimized device measured at forward and reverse scan. device

control

6%

Scan

Jsc/mA

direction

cm-2

Voc/V

FF

η(%)

Hysteresis index

Forward

20.9

1.09

0.6

13.7

Reverse

21.2

1.09

0.7

16.2

Forward

22.3

1.13

0.68

17.2

Reverse

22.3

1.13

0.75

18.9

0.15

0.09

To further reveal the reasons for the enhanced device performance, we investigated the PL and time-resolved PL of the MAPbI3 films coated on glass substrates with or without ACN additive. The steady-state PL was shown in Figure 5a. It presents that the MAPbI3 film with 6% ACN shows higher PL intensity than that of the pristine sample, which indicates reduced non-radiation recombination channel in the perovskite film due to reduced grain boundaries and thus trap states. In addition, the carrier extraction at MAPbI3/SnO2 (Spiro-OMeTAD) interface was also investigated. As shown in Figure S7, the PL intensity for the SnO2/MAPbI3 (w ACN) and MAPbI3 (w ACN)/Spiro-OMeTAD both decreased compared with the control samples, indicating better carrier extraction at the two interfaces. The TRPL spectrums of the MAPbI3 films were presented in Figure 5b. By the following attenuation equation, we can estimate the charge carrier lifetime: Y=γ0+A1 (-t/τ1)+A2 exp(-t/τ2) (1) In equation (1), A1 and A2 are the decay amplitude, τ1 represents the fast recombination lifetime, τ2 is the lifetime of slow recombination caused by the trap12 ACS Paragon Plus Environment

Page 13 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


induced recombination and the γ0 is a basal constant.37 The fitted τ1 and τ2 for the control perovskite film are 4.57 ns and 110.4 ns respectively. While, the perovskite film with 6% CAN exhibits the τ1 and τ2 of 4.7 ns and 183.3 ns respectively. The larger τ2 indicates the reduced defects and thus trap-induced charge recombination. This is responsible for the improved device performance above.

Figure 5. (a) The steady PL of the perovskite films deposited on glass substrates, (b) the TRPL spectra of the corresponding perovskite films.

We further analyzed the J-V characteristics of the two champion devices prepared with and without 6% ACN based on the diode theory. It has been reported that the dark saturate current density (J0) and series resistance Rs can be derived from the liner fitting plot of ln (Jsc-J) vs (V+RsJ) and –dV/dJ vs (Jsc-J)-1, respectively.38 As can be seen from the Figure 6a, b, the Rs for the device with and without 6% ACN are calculated to be 2.14 and 2.39 Ω cm2 respectively. In addition, the derived J0 for the corresponding device is 5×10-7 and 9.1×10-5 mA cm-2, respectively. The decreased Rs for the device with ACN additive can be ascribed to the improved perovskite film, which is benefit for the carrier transport. On the other hand, the J0 is directly 13 ACS Paragon Plus Environment


Page 14 of 28

connected with the carrier recombination, the smaller J0 for the ACN modified device suggested reduced recombination loss, explaining the higher FF and Voc.38 Then we performed the space-charge-limited current (SCLC) measurement to estimate the trap density in the devices prepared without and with 6% ACN additive. Figure 6c presents the dark logarithmic I-V plots of the electron-only devices, of which the configuration is FTO/SnO2/MAPbI3 (w or wo 6% ACN additive)/PC61BM/Ag. As the previous literature report, the trap density (nt) in the device is related to the onset voltage value of VTFL (trap-filled-limited, TFL) according to the following equation: VTFL =entL2/2εε0 (2) In equation (2), e is elementary electric charge, L shows the thickness of MAPbI3 layer, ε is the dielectric constant of MAPbI3 and ε0 represents the vacuum permittivity.16, 24 It is observed that the VTFL for the electron-devices with and without 6% ACN additive is 0.32 and 0.39 V, respectively. Therefore, the derived trap density for the corresponding devices is 6.2×1015 cm-3 and 7.7×1015 cm-3, respectively. This result further reveals that the introduced ACN additive can lower the defects in perovskite film due to the grain coarsening effect. In addition, the electron mobility (μ) can be calculated by the Mott-Gurney law in the SCLC region: J=9εε0μV2/8L3 (3)


Page 15 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The μ of the devices with and without 6% ACN was extrapolated to be 8.5 × 10-3 cm2 V-1 s-1 and 3.7 × 10-3 cm2 V-1 s-1, respectively. The increased electron mobility can be ascribed to the improved quality of the perovskite film and reduced trap sites induced by ACN. In addition, the hole transport property in the device was also investigated by fabricating the hole-only devices (ITO/PEDOT:PSS/MAPbI3(with and without ACN)/Spiro-OMeTAD/Ag). As can be seen in the Figure S8, the calculated μh for the MAPbI3 treated by CB/ACN antisolvent increased from 0.6×10-3 cm2 V-1 s-1 (pristine MAPbI3) to 1.8×10-3 cm2 V-1 s-1. Then, we further calculated the ratio of electron and hole mobility (μe/μh) for the two devices. The results shows that the μe/μh decreased from 6.2 for control device to 4.7 after introducing ACN, indicating the more balanced charge transport. Finally, to further assess the carrier transport and recombination in both devices, the impedance spectroscopy of both devices was measured under dark condition with frequency raging from 20 Hz to 20 MHz. Figure 6d shows the Nyquist plots of the corresponding devices with and without 6% ACN and the equivalent circuit model are presented as inset. As can be seen, the Nyquist plots include two diacritical characteristic arcs, corresponding to the contact resistance (Rco) at perovskite/HTM (ETL) interfaces in high frequency region and the recombination resistance (Rrec) in low frequency region.24,

39

The device with 6%

ACN shows a larger Rrec value than that of the control device, and the extracted Rco



Page 16 of 28

value for the devices with and without ACN are 63.1Ω and 354.2 Ω, respectively. These results demonstrate that the introduced ACN not only effectively improve the contact at perovskite/HTM (ETL) interfaces due to improved perovskite film quality but also suppress the carrier recombination in the devices, which are supposed to be the main reason for lower Rs and higher efficiency in the optimized device.

Figure 6. (a) Plot of –dV/dJ vs (Jsc-J)-1 and liner fitting and (b) ln (Jsc-J) vs (V+RsJ) and linear fitting for the champion device with and without ACN additive. (c) The dark I-V measurement of the corresponding electron-only devices. (d) The Nyquist plots of the devices with and without ACN measured under dark condition.


Page 17 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CONCLUSIONS In conclusion, we proposed a facile method to fabricate high quality perovskite film with increased grain size by adding ACN additive in the CB anti-solvent. The results show that ACN additive plays an important role in the perovskite crystallization, which could effectively rationalized the ratio of DMSO in the intermediate phase, leading to the formation of uniform MAPbI3 with larger grain size and lower density of traps. This is beneficial for the carrier transport and reduction of carrier recombination losses in the device. Based on these aspects, the device based on the modified MAPbI3 prepared with ACN/CB mixed antisolvent shows the highest PCE of 18.9% with less hysteresis in comparison with that (16.2%) for the control device. In addition, the air stability of the modified devices was enhanced obviously due to the improvement of the MAPbI3 film, which could still keep the 80% of the initial PCE for 17 days in ambient atmosphere with humidity of 20%. This work provides a facile method for preparing high-quality perovskite film and further improving the device performance.



Page 18 of 28

ASSOCIATED CONTENT

Supporting Information

The experimental section. The average grain size of the perovskite film prepared with different volume ration of ACN/CB antisolvent (X=0%, 2%, 4%, 6%, 8%, 12%). The AFM of the MAPbI3 films prepared with or without ACN. The enlarged region of (110) peak in XRD pattern and the corresponding FWHM of the (110) diffraction peaks for the MAPbI3. The ration of intensity of the absorbance at 1019 and 3193 cm1

(1019 cm-1:3193 cm-1). The UV-vis absorption of the perovskite films prepared with

different ACN in chlorobenzene. The detailed photovoltaic parameters of the devices prepared with different ACN in chlorobenzene. The J-V curves for the control and optimized device measured with different delay time. The detailed photovoltaic parameters with different delay time. The PL spectra of ITO/MAPbI3 (w/o, w ACN)/Spiro-OMeTAD and ITO/SnO2/MAPbI3 (w/o, w ACN). The I-V curves measured with the space-charged limited current for the hole-only devices based on the structure of ITO/PEDOT:PSS/MAPbI3 (with and without ACN)/SpiroOMeTAD/Ag.

AUTHOR INFORMATION Corresponding Authors


Page 19 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Email: [email protected]: +86-138-4317-8907. ORCID Shanpeng Wen: 0000-0001-5114-6307 Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS

This work was supported by the National Natural Science Foundation of China (Grant No. 61874048), the Jilin Provincial Department of education “13th Five-Year” science and technology project (JJKH20180121KJ), the Project of Science and Technology Development Plan of Jilin Province (Grant No. 20180414020GH), the Project of Jilin Provincial Development and Reform Commission (2018C040-2), and Opened Fund of the State Key Laboratory on Applied Optics.



Page 20 of 28

REFERENCES

[1] Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050-6051.

[2] Jeon, N. J.; Na, H.; Jung, E. H.; Yang, T. Y.; Lee, Y. G.; Kim, G.; Shin, H. W.; Seok, S. I.; Lee, J.; Seo, J. A Fluorene-Terminated Hole-Transporting Material for Highly Efficient and Stable Perovskite Solar Cells. Nat. Energy 2018, 3, 682-689.

[3] Yang, W. S.; Park, B. W.; Jung, E. H.; Jeon, N. J.; Kim, Y. C.; Lee, D. U.; Shin, S. S.; Seo, J. W.; Kim, E. K.; Noh, J. H.; Seok, S. I. Iodide Management in Formamidinium-Lead-Halide-Based Perovskite Layers for Efficient Solar Cells. Science 2017, 356(6345), 1376-1379.

[4] Xie, J. S.; Huang, K.; Yu, X. G.; Yang, Z. R.; Xiao, K.; Qiang, Y. P.; Zhu, X. D.; Xu, L. B.; Wang, P.; Cui, C.; Yang, D. R. Enhanced Electronic Properties of SnO2 via Electron Transfer from Grapheme Quantum Dots for Efficient Perovskite Solar Cells. ACS Nano 2017, 11(9), 9176-9182.

[5] Tan, H. R.; Jain, A.; Voznyy, O.; Lan, X. Z.; Arquer, F. P. G. D.; Fan, J. Z.; Bermudez, R. Q.; Yuan, M. J.; Zhang, B.; Zhao, Y. C.; Fan, F. J.; Li, P. C.; Quan, L. N.; Zhang, Y. B.; Lu, Z. H.; Yang, Z. Y.; Hoogland, S.; Sargent, E. H. Efficient and


Page 21 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Stable Solution-Processed Planar Perovskite Solar Cells via Contact Passivation. Science 2017, 355(6326), 722-726.

[6] Song, S.; Kang, G.; Pyeon, L.; Lim, C.; Lee, G. Y.; Park, T.; Choi, J. M. Systematically Optimized Bilayered Electron Transport Layer for Highly Efficient Planar Perovskite Solar Cells (#=21.1%). ACS Energy Lett. 2017, 2(12), 2667-2673.

[7] Stranks, S. D.; Eperon, G. E.; Grancini, G.; Menelaou, C.; Alcocer, M. J. P.; Leijtens, T.; Herz, L. M.; Petrozza, A.; Snaith, H. J. Electron-Hole Diffusion Lengths Exceeding 1 Micrometer in an Organometal Trihalide Perovskite Absorber. Science 2013, 342, 341-344.

[8] Zhu, W. D.; Kang, L.; Lv, B. H.; Wang, Y. R. Q.; Chen, X. Y.; Wang, X. Y.; Zhou, Y.; Zou, Z. G. Facile Face-down Annealing Triggered Remarkable Texture Development in CH3NH3PbI3 Films for High-Performance Perovskite Solar Cells. ACS Appl.Mater. Interfaces 2017, 9(7), 6104-6113.

[9] Meggiolaro, D.; Motti, S. G.; Mosconi, E.; Barker, A. J.; Ball, J.; Perini, C. A. R.; Deschler, F.; Petrozza, A.; Angelis, F. D. Iodine Chemistry Determines the Defect Tolerance of Lead-Halide Perovskites. Energy Environ. Sci. 2018, 11, 702-713.

[10] Kandada, A. R. S.; Petrozza, A. Photophysics of Hybrid Lead Halide Perovskite: The Role of Microstructure. Acc. Chem. Res. 2016, 49(3), 536-544. 21 ACS Paragon Plus Environment


Page 22 of 28

[11] Buin, A.; Pietsch, P.; Xu, J. X.; Voznyy, O.; Ip, A. H.; Comin, R.; Sargent, E. H. Materials Processing Routes to Trap-Free Halide Perovskites. Nano Lett. 2014, 14, 6281-6286.

[12] NREL. Best Research-Cell Efficiency Chart. https://www.nrel.gov/pv/cellefficiency .

[13] Kim, J.; Lee, S. H.; Lee, J. H.; Hong, K. H. The Role of Intrinsic Defects in Methylammonium Lead Iodide Perovskite. J. Phys. Chem. Lett. 2014, 5(8), 13121317.

[14] Liu, C.; Huang, Z. Q.; Hu, X. T.; Meng, X. C.; Huang, L. Q.; Xiong, J.; Tan, L. C.; Chen, Y. W. Grain Boundary Modification via F4TCNQ to Reduce Defects of Perovskite Solar Cells with Excellent Device Performance. ACS Appl. Mater. Interfaces 2018, 10(2), 1909-1916.

[15] Guo, Q.; Yuan, F. L.; Zhang, B.; Zhou, S. J.; Zhang, J.; Bai, Y. M.; Fan, L. Z.; Hayat, T.; Alsaedi, A.; Tan, Z. A. Passivation of The Grain Boundaries of CH3NH3PbI3 Using Carbon Quantum Dots for Highly Efficient Perovskite Solar Cells with Excellent Environmental Stability. Nanoscale 2019, 11, 115-124.


Page 23 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[16] Guo, Y. X.; Ma, J. J.; Lei, H. W.; Yao, F.; Li, B. R.; Xiong, L. B.; Fang, G. J. Enhanced Performance of Perovskite Solar Cells via Anti-Solvent Nonfullerene Lewis Base IT-4F Induced Trap-Passivation. J. Mater. Chem. A 2018, 6, 5919-5925.

[17] Liu, L.; Huang, S.; Lu, Y.; Liu, Y.; Liu, P. F.; Zhao, Y. Z.; Shi, C. B.; Zhang, S. Y.; Wu, J. F.; Zhong, H. Z.; Sui, M. L.; Zhou, H. P.; Jin, H. B.; Li, Y. J.; Chen, Q. Grain-Boundary “Patches” by in Situ Conversion to Enhance Perovskite Solar Cells Stability. Adv. Mater. 2018, 30(29), 1800544.

[18] Wei, D.; Ma, F. S.; Wang, R.; Dou, S. Y.; Cui, P.; Huang, H.; Ji, J.; Jia, E. D.; Jia, X. J.; Sajid, S.; Elseman, A. M.; Chu, L. H.; Li, Y. F.; Jiang, B.; Qiao, J.; Yuan, Y. B.; Li, M. C. Ion-Migration Inhibition by The Cation-π Interaction in Perovskite Materials for Efficient and Stable Perovskite Solar Cells. Adv. Mater. 2018, 30(31), 1707583.

[19] Sun, Q.; Fassl, P.; Koch, D. B.; Bausch, A.; Rivkin, B.; Bai, S.; Hopkinson, P. E.; Snaith, H. J.; Vaynzof, Y. Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films. Adv. Energy Mater. 2017, 7, 1700977.

[20] Zhang, F.; Bi, D. Q.; Pellet, N.; Xiao, C. X.; Li, Z.; Berry, J. J.; Zakeeruddin, S. M.; Zhu, K.; Grätzel, M. Suppressing Defects Through The Synergistic Effect of a



Page 24 of 28

Lewis Base and a Lewis Acid for Highly Efficient and Stable Perovskite Solar Cells. Energy Environ. Sci. 2018, 11, 3480-3490.

[21] Yang, M. J.; Zhang, T. Y.; Schulz, P.; Li, Z.; Li, G.; Kim, D. H.; Guo, N. J.; Berry, J. J.; Zhu, K.; Zhao, Y. X. Facile Fabrication of Large-Grain CH3NH3PbI3-xBrx Films for High-Efficiency Solar Cells via CH3NH3Br-Selective Ostwald Ripening. Nat. Commun. 2016, 7, 12305.

[22] Li, Y. W.; Zhao, Y.; Chen, Q.; Yang, Y.; Liu, Y. S.; Hong, Z. R.; Liu, Z. H.; Hsieh, Y. T.; Meng, L.; Li, Y. F.; Yang, Y. Multifunctional Fullerene Derivative for Interface Engineering in Perovskite Solar Cells. J. Am. Chem. Soc. 2015, 137, 1554015547.

[23] Bi, D. Q.; Li, X.; Milić, J. V.; Kubicki, D. J.; Pellet, N.; Luo, J. S.; Grange, T. L.; Mettraux, P.; Emsley, L.; Zakeeruddin, S. M.; Grätzel, M. Multifunctional Molecular Modulators for Perovskite Solar Cells with over 20% Efficiency and High Operational Stability. Nat. Commun. 2018, 9(1), 4482.

[24] Niu, T. Q.; Lu, J.; Munir, R.; Li, J. B.; Barrit, D.; Zhang, X.; Hu, H. L.; Yang, Z.; Amassian, A.; Zhao, K.; Liu, S. Z. Stable High-Performance Perovskite Solar Cells via Grain Boundary Passivation. Adv. Mater. 2018, 30(16), 1706576.


Page 25 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[25] Zheng, X. P.; Chen, B.; Dai, J.; Fang, Y. J.; Bai, Y.; Lin, Y. Z.; Wei, H. T.; Zeng, X. C.; Huang, J. S. Defect Passivation in Hybrid Perovskite Solar Cells Using Quaternary Ammonium Halide Anions and Cations. Nat. Energy 2017, 2(7), 17102.

[26] Jiang, J. X.; Wang, Q.; Jin, Z. W.; Zhang, X. S.; Lei, J.; Bin, H. J.; Zhang, Z. G.; Li, Y. F.; Liu, S. Z. Polymer Doping for High-Efficiency Perovskite Solar Cells with Improved Moisture Stability. Adv. Energy Mater. 2018, 8, 1701757.

[27] Ke, W.; Xiao, C.; Saparov, B.; Duan, H. S.; Zhao, D.; Xiao, Z.; Schulz, P.; Harvey, S. P.; Liao, W.; Meng, W.; Yu, Y.; Cimaroli, A. J.; Jiang, C. S.; Zhu, K.; AlJassim, M.; Fang, G.; Mitzi, D. B.; Yan, Y.; Employing Lead Thiocyanate Additive to Reduce The Hysteresis and Boost The Fill Factor of Planar Perovskite Solar Cells. Adv. Mater. 2016, 28(26), 5214-5221.

[28] Feng, J. S.; Zhu, X. J.; Yang, Z.; Zhang, X. R.; Niu, J. Z.; Wang, Z. Y.; Zou, S. N.; Priya, S.; Liu, S. Z.; Yang, D. Record Efficiency Stable Flexible Perovskite Solar Cell Using Effective Additive Assistant Strategy. Adv. Mater. 2018, 30, 1801418.

[29] Numata, Y.; Kogo, A.; Udagawa, Y.; Kunugita, H.; Ema, K.; Sanethira, Y.; Miyasaka, T. Controlled Crystal Grain Growth in Mixed Cation-Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells. ACS Appl. Mater. Interfaces 2017, 9(22), 18739-18747.



Page 26 of 28

[30] Bi, C.; Shao, Y. C.; Yuan, Y. B.; Xiao, Z. G.; Huang, J. S. Non-Wetting Surface-Driven High-Aspect-Ratio Crystalline Grain Growth for Efficient Hybrid Perovskite Solar Cells. Nat. Commun. 2015, 6, 7747.

[31] Jeon, N. J.; Noh, J. H.; Kim, Y. C.; Yang, W. S.; Ryu, S.; Seok, S. I. Solvent Engineering for High-Performance Inorganic-Organic Hybrid Perovskite Solar Cells. Nature Mater. 2014, 13(9), 897-903.

[32] Ahn, N.; Son, D. Y.; Jang, I. H.; Kang, S. M.; Choi, M.; Park, N. G. Highly Reproducible Perovskite Solar Cells with Average Efficiency of 18.3% and Best Efficiency of 19.7% Fabricated via Lewis Base Adduct of Lead(II) Iodide. J. Am. Chem. Soc. 2015, 137(27), 8696-8699.

[33] Saliba M.; Correa-Baena J. P.; Wolff, C. M.; Stolterfoht, M.; Phung, N.; Albrecht, S.; Neher, D.; Abate, A. How to Make Over 20% Efficient Perovskite Solar Cells in Regular (n-i-p) and Inverted (p-i-n) Architectures. Chem. Mater. 2018, 30(13), 4193-4201.

[34] Yang, F.; Kapil, G.; Zhang, P. T.; Hu, Z. S.; Kamarudin, M. A.; Ma, T. L.; Hayase, S. Dependence of Acetate-Based Antisolvents for High Humidity Fabrication of CH3NH3PbI3 Perovskite Devices in Ambient Atmosphere. ACS Appl. Mater. Interfaces 2018, 10, 16482-16489.


Page 27 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[35] Wang, Y. F.; Wu, J.; Zhang, P.; Liu, D. T.; Zhang, T.; Ji, L.; Gu, X. L.; Chen, Z. D.; Li, S. B. Stitching Triple Cation Perovskite by a Mixed Anti-Solvent Process for High Performance Perovskite Solar Cells. Nano Energy 2017, 39, 616-625.

[36] Li, L. F.; Zhou, P.; Li, J.; Mo, Y. P.; Huang, W. C.; Xiao, J. Y.; Li, W.; Ku, Z. L.; Zhong, J.; Peng, Y.; Cheng, Y. B.; Huang, F. Z. Suppressed Hysteresis and Enhanced Performance of Triple Cation Perovskite Solar Cell with Chlorine Incorporation. J. Mater. Chem. C 2018, 6, 13157-13161.

[37] Li, F. C.; Yuan, J. Y.; Ling, X. F.; Zhang, Y. N.; Yang, Y. G.; Cheung, S. H.; Ho, C. H. Y.; Gao, X. Y.; Ma, W. L.; A Universal Strategy to Utilize Polymeric Semiconductors for Perovskite Solar Cells with Enhanced Efficiency and Longevity. Adv. Funct. Mater. 2018, 28(15), 1706377.

[38] You, J. B.; Yang, Y.; Hong, Z. R.; Song, T. B.; Meng, L.; Liu, Y. S.; Jiang, C. Y.; Zhou, H. P.; Chang, W. H.; Li, G.; Yang, Y. Moisture Assisted Perovskite Film Growth for High Performance Solar Cells. Appl. Phys. Lett. 2014, 105, 183902.

[39] Bu, T. L.; Li, J.; Zheng, F.; Chen, W. J.; Wen, X. M.; Ku, Z. L.; Peng, Y.; Zhong, J.; Cheng, Y. B.; Huang, F. Z. Universal Passivation Strategy to Slot-Die Printed SnO2 for Hysteresis-Free Efficient Flexible Perovskite Solar Module. Nat. Commun. 2018, 9(1), 4609.



Page 28 of 28

For TOC only


High-efficiency and stable perovskite solar cells prepared using

Recommend Documents