Trends Analysis of Graphene Research and Development

The country/region distribution of publications was produced as Figure 2. Those with total numbers of over 2000 are shown in red. Five top producers are China (excluding Hong Kong, Macao and Taiwan, similarly hereinafter), United States, South Korea, Japan and India. They together accounted for 64.3 percent of the global total. The distribution of patent applicant countries was also analyzed where the top five countries are China, South Korea, United States, Japan and Germany. They together accounted for over 90 percent of the global patents in graphene.

Figure 2

Figure 3 gives the relative outputs of the top five countries from 2000 to 2015. From the retrieved data, we know that the United States and Japan published their first papers in graphene in 1985 and 1992, respectively, and went strong until around 2010 when their publications began level-off and even began to decline after 2013. In contrast, publications from China has grown dramatically after 2010, surpassing the United States. The publications from South Korea overtook Japan since 2010, but increased only slowly afterwards, to be in similar strength as India in recent years. Nearly half of the publications from China and South Korea were produced during 2013–2015.

Figure 3

As for patent applications, data since 2001 were shown in Figure 4 for the top five countries identified in Figure 2. The United States and Japan applied their first patents in 1997 and 1999, respectively, but their applications began to drop considerably around 2008–2010. In contrast, the number of patents applied from China started since 2007 and increased dramatically ever since, with 2012 saw that China applied more than 50% of the world total, while the other four countries faced steady declination.

Figure 4

Figure 5 illustrates the flows of patent applications among the top five countries. The width of the arrows is proportional to the patent applications originated from one country to be applied in other countries. The majority of patent applications flew to United States and China. Although the total number of patent applications of China is high, only 2.3 percent of them are done in other countries. In contrast, the ratios that Korea, United States, Japan and Germany applied patents in other four countries are 27.8%, 24.8%, 32.3% and 45.3%, respectively. While Chinese institutes applied the largest number of patents, most were applied only in China.

Figure 5

Table 1 lists the top 20 organizations in terms of publications, 11 are in China, three in the United States, two in South Korea, two in Singapore, one each from Japan and Russia. 18 out of the 20 are universities, while the remaining two are research institutes, indicating that graphene research is dominated by universities and research institutes.

Table 1

Top 20 organizations in graphene research papers.

Major research topics for each of the top 20 were obtained using methods described in Section 2. It shows that Chinese organizations mainly focus on sensors, electronics and photovoltaics, and batteries, while US ones concentrated more on photoelectric properties, electronic structure, thin film transistors and semiconductors. Organizations from South Korea deal more on capacitors while the Japanes one focuses on electric properties.

20 top global graphene patent applicants are listed in Table 2. Among them, 14 were from China, four from South Korea and two from the United States. In addition, 15 assignees were universities or research institutes while the other five were enterprises.The top five were Chinese Academy of Sciences, Samsung Electronics, Ocean’s King Lighting Science & Technology, Zhejiang University, and LG Electronics. The major technology topics of patent applications for the top 20 organizations indicated that Chinese assignees applied patents more in preparation, batteries and composites, while the assignees from South Korea focused mainly in semiconductors devices and batteries and those from the United States primarily in semiconductors devices.

Table 2

Top 20 applicants in graphene research papers.

The evolution of graphene research topics was analyzed using the concepts of papers and patents indexed by CAS. Considering the dramatic increase after 2010, the data set was divided into two time windows, 1985–2009 and 2010–2016 (Figure 8 and 9, respectively). Two networks show that before 2009, graphene research mainly focused on the mechanical and other properties and electrical properties. But since 2010, it has extended continuously into a diverse range of potential applications, such as batteries, capacitors, semiconductors, and sensorsdevices.

Figure 8

Figure 9

Indexed concepts in papers and patents were analyzed to detect emerging concepts and their percentages among all the indexed terms, in four periods: before 2009, 2010–2011, 2012–2013, and 2014 and after, as in Figure 10. The sizes of the pie charts are proportional to the numbers of concepts and the orange color parts represent the percentages of emerging terms. Emerging concepts increased remarkably after 2010 and the trend correlated with widening of research and innovation into diverse fields, indicating the vitality of graphene R&D and potential for new break-throughs.

Figure 10

Substance roles indexed by CAS in the papers and patents were examined (Figure 11). 39.9 percent are USES, including TEM (Technical or Engineered Material Use), MOA (Modifier or Additive Use), CAT (Catalyst Use), NUU (Other Use, Unclassified); 20.8 percent are Special, including PRP (Properties) and NAN (Nanoscale Substances/Materials); 18.6 percent are PROC (Process), including PEP (Physical, Engineering or Chemical Process) and REM (Removal or Disposal).

Figure 11

Time distribution for substances roles was given in Figure 12. PRP (Properties) has declined since 2006; NAN (Nanoscale Substances/Materials), IMF (Industrial Manufacture), RGT (Reagent), CAT (Catalyst Use) have decreased since 2009; PEP (Physical, Engineering or Chemical Process) has remained constant since 2011; TEM (Technical or Engineered Material Use), ANT (Analyte), BSU (Biological Study, Unclassified), POF (Polymer in Formulation) have decreased since 2012. In contrast, BUU (Biological Use, Unclassified) has increased since 2008, MOA (Modifier or Additive Use), POL (Pollutant) and REM (Removal or Disposal) grew year on year. In general, the main roles declined recently while roles in Biological Use, Modifier or Additive Use, Pollutant, Removal or Disposal have become new focuses.

Figure 12

Time slice analysis was used to examine the evolution of emerging substance roles in graphene research (Figure 13). Based on the emerging substances, roles in USES and PROC (Process) have declined in recent years. On the contrary, the roles in PREP (Preparation) and BIOL (Biological Study) increased over time.

Figure 13