Retraction Watch

Tracking retractions as a window into the scientific process

Data irregularities force author to retract three solar cell papers

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An engineer has retracted three papers on a method for making nanoscale materials that are useful in solar cells.

The papers, all published in ACS Applied Materials & Interfaces, contain irregularities in data, and one includes images “which have been published elsewhere and identified with different samples,” according to the note.

The first author on all three papers is Khalid Mahmood, who — according to the bio from a talk he gave last year on efficient solar cells — is currently a postdoc at King Abdullah University of Science and Technology in Saudi Arabia. He did the work in the retracted papers while a student at the Korea Advanced Institute of Science and Technology, where, according to the bio, he completed his PhD in two years.

Here’s the retraction note for the first paper (which also contains a typo in the title — “electrospay”)

The authors retract the article “Fabrication of Tantalum and Nitrogen Codoped ZnO (Ta, N-ZnO) Thin Films Using the Electrospray: Twin Applications as an Excellent Transparent Electrode and a Field Emitter,” ACS Appl. Mater. Interfaces 2013, 5, 3722−3730, DOI: 10.1021/am4003342, on the basis of irregularities in the EDX data in Figure 2 and the XPS data in Figure 3a. Specifically, similarities in the noise in the two EDX spectra reported in Figure 2 and in the noise in the XPS data in Figure 3a compared with Figure 5b in J. Mater. Chem. C, 2013, 1, 3138−3149, DOI: 10.1039/C3TC00082F, cast doubt on the validity of these data.

That paper has been cited four times, according to Thomson Scientific’s Web of Knowledge.

Kirk Schanze, the editor in chief of the journal, told us how the issues came to light:

The allegation of irregularities in the data were noted by a reader of ACS Applied Materials & Interfaces. As with all inquiries of this nature, the editorial office reviewed the allegations and contacted the authors. Upon further investigation, it was confirmed with the author that the irregularities rendered the data invalid and the article was thus retracted by the authors.

Here’s the retraction note for the next paper, which has been cited 16 times:

The authors retract the article “Hydrothermally Grown Upright-Standing Nanoporous Nanosheets of Iodine-Doped ZnO (ZnO:I) Nanocrystallites for a High-Efficiency DyeSensitized Solar Cell”, ACS Appl. Mater. Interfaces 2013, 5 (8), 3075−3084, DOI: 10.1021/am303272g, on the basis of uncertainties in the validity of the SEM images, which have been published elsewhere and identified with different samples. Specifically, Figure 1b in the present article, identified as Idoped ZnO, is the same image as Figure 2e in Surface and Coating Technology 2012, 206, 4730−4740, DOI: 10.1016/ j.surfcoat.2012.01.047, where it is identified as Ta-doped ZnO. Similarly, Figure 4a in the present article, identified as I-doped ZnO, is the same image as Figure 3d in Surface and Coating Technology 2012, 206, 4730−4740, DOI: 10.1016/j.surfcoat.2012.01.047, where it is identified as undoped ZnO.

And the retraction note for the third paper, which has been cited five times:

The authors retract the article “Polyethylenimine-Assisted Growth of High-Aspect-Ratio Nitrogen-Doped ZnO (NZO) Nanorod Arrays and Their Effect on Performance of Dye-Sensitized Solar Cells”, ACS Appl. Mater. Interfaces 2014, 6 (13), pp 10028−10043, DOI: 10.1021/am500105x, on the basis of irregularities in the EDX data in Figure 9. Specifically, similarities in the noise in the two EDX spectra reported in Figure 9 cast doubt on the validity of these data.

The last author on that paper, Hyun Suk Jung, who worked with Mahmood briefly at Sungkyunkwan University in Korea, forwarded us a letter he sent to editor Schanze. In the letter, he says that he hadn’t been aware with issues with the paper: 

I am very shocked because I have never imagined that I would be involved in this kind of issue.

He writes,

Regarding the EDX data, I would like to let you know how I tried to resolve the issue. First, I contacted Dr. Khalid to investigate the reliability of the date. I asked how he obtained the EDX data for the paper and requested him to send the original raw data. Instead of providing raw data, he replied that his friend took data for him, but did not reveal any detail of the data (a person who did EDS work, experimental conditions, data treatment method for publication etc.). He argues that there is no problem with EDS data in Figure 9 and he can repeat the experiment to prove his old results.. As of today, he failed to send me any convincing data to prove that the similarity in Fig. 9 originates from statistical uncertainty.

And concludes,

as one of corresponding authors, I feel dishonored to be involved in an issue of academic integrity. I should have checked all of data in the paper and confirmed their reliability before submission. Whether the data are true or false, Dr. Khalid does not show full responsibility for published data. Since I have not received the raw data from Dr. Khalid so far, I as one of corresponding authors, would suggest retracting the paper. I will fully follow the decision which the editorial board will make on this paper.

We’ve reached out to Mahmood and to Seung Bin Park, the corresponding author on two of the papers, affiliated with KAIST. 

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