Peer review of: A bilateral interfacial passivation strategy promoting efficiency and stability of perovskite quantum (2020)


RR2
 Reviewers' comments:
Reviewer #1 (Remarks to the Author):
The authors have tried their best to address the issues mentioned by the Reviewers, the paper can be
 accepted for publication now.
Reviewer #2 (Remarks to the Author):
The authors have addressed major comments. However these concerns remain in the revised work:
  
   1. The authors use vacuum-evaporated TSPO1, DPEPO and TPPO to passivate the perovskite QD layer,
 but spin-cast TPPO has been recently reported to passivate reduced-dimensional perovskites (Nature
 Communications, 2020, 11, 170), so I am not sure whether the present submission is novel enough.
 2. The authors now use DMAC-DPS (S=O) for comparison. I wonder whether there is an extra
 emission peak from DMAC-DPS in EL spectra of the corresponding LEDs? How about other C=O or
 N=O molecules? Can they also passivate QDs? Please provide more evidence of the passivation
 mechanism.
 3. The authors now provide comparison between POOM/QD, POOM/QD/POOM and QD/POOM, but one
 concern is that the solvent to spin-coat QD, i.e. n-octane, may dissolve POOM and destroy the device
 structure. How did the authors address this problem?
 4. The authors should provide details of fabricating electron-only devices, and explain how they
 prepare QD layer using n-octane on TPBi without destroying the lower film.
 Reviewer #3 (Remarks to the Author):
 The authors responded referee's comments in detail with more interesting results. They also have
 made a lot of revision in the revised version. I think the article is sufficient for its acceptance in the
 journal after solving some remaining problems:
 1. Figure R16, R23 and Figure S10 are the same figure, but the caption and description on Figure R16
 and R23 in the rebuttal file is not consistent with the related Figure S10 in Supporting Information and
 Revised Manuscript.
 Figure R16: The PL stabilities of pure CsPbBr3 QD film, and QD film under unilateral passivation,
 bilateral passivation respectively
 Figure R23: The PL attenuation of QD film under the atmosphere with RH 40%.
 Figure S10: The PL stability of pristine and bilateral passivated QD films excited by 365 nm.
 2. could the trap density be quantified by other widely used methods other than the space-charge-
 limited-current (SCLC) technique? such as Drive-level capacitance profiling (DLCP)?
 Reviewer #4 (Remarks to the Author):
This paper by Xu et al describes the role of bifacial passivation on perovskite QD leds. Authors have
 
 responded to many questions raised by the reviewers, which is highly appreciated. However, after
 going over all the questions raised by the referees and looking at some of the results, I do not still
 believe that this paper adds a substantially to the large literature on perovskite based LEDs. The
 authors report a high QE approaching 20% but the stability is of the order of minutes, even after
 passivation. The stability of perovskite LEDs is the biggest open question and this has not been
 addressed. Also, this has been measured at 1000 Cd while the peak is 21000 Cd. This is 1/20 th of the
 efficiency.
 There are also measurements on measuring the times resolved PL with and without passivation and
 these hardly change in their lifetime. In fact, if the authors fit the curve, they will find that the lifetime
 is identical. Also, the defect density measured is 2x1018/cm3, which is high. The authors claim a
 reduction in defect density from 2 to 1x1018/cm3. This is within error. This suggests that the
 passivation does not seem to affect the charge recombination within the film.
 I do not see what is the new science that would move the field of perovskite based LEDs forward and
 therefore do not believe that this paper should be published in Nature Communications.