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 Since the 21st Century, multi-point breakthroughs and cross-integration of information, biology, new energy, new materials have laid the foundation for a new round of industrial revolution. Technological convergence has become an important symbol of the rapid rise of new industries and new business forms, and has an important impact on the development of new technologies and new products that cannot be ignored. For example, the deep fusion of biotechnology and nanotechnology has created a new bio-nanotechnology that opens up research and market space for a variety of disruptive new drugs (e.g. monoclonal antibody drug zevalin and targeted drug delivery technology Doxil for cancer treatment). The combination of pharmaceutical technology and food manufacturing technology has created a functional food industry, and the combination of pharmaceutical technology and cosmetic manufacturing technology has created a cosmeceuticals industry. However, technology convergence may also lead to some new socioeconomic problems. Such as the integration of intelligent robotics and traditional manufacturing greatly improves production efficiency, but also replacing the traditional labor-intensive production technology. "Internet finance" has created a new financial service model with great market potential, but it has also led to the squeeze on the traditional financial industry. The mode of technological innovation has gradually changed from the traditional mode of scientific breakthrough to the mode of technological fusion. Therefore, scientific and objective analysis of cross-field technology convergence is of great research significance and scientific value in guiding major disruptive technological innovation and new product development.

Technology convergence refers to the phenomenon that the originally independent technologies cross their boundaries penetrate each other to give birth to new technologies. As the core power of industrial transformation, technology convergence is considered as the important factor to promote formation of emerging industries and development of new products. In recent years, technology convergence has been widely concerned by scholars, although some scholars have put forward the theoretical concept of complementarity and substitution, because of the inherent fuzziness and complexity of the fusion phenomenon, the measurement and analysis of technology fusion are difficult. The quantitative investigation of its impact on new product development performance is seldom studied. Therefore, how to use scientific methods and objective data to compare and analyze the internal characteristics of complementarity and substitution technologies convergence and the impact mechanism on the performance of enterprise new product development needs to be solved urgently. Based on the panel data about new products, patents and enterprise characteristics of 343 new energy automobile enterprises in China from 2005 to 2017, this paper measures complementarity and substitution technology convergence by coupling structure and substitution relation of patents′ IPC, and empirically analyzes the relationship between cross-domain technology convergence and new product development performance of corporations, by applying fixed- effect negative binomial regression model. The results show that: (1) There is a positive relationship between the substitution technology convergence and the performance of new product development of firms. This is because when enterprises integrate alternative technologies, the relevance between technologies can help enterprises endow original technologies with new additional functions and stronger competitiveness in a relatively short time, thus accelerating the optimization of product system performance. At the same time, the compatibility between similar technical elements can effectively improve the reliability and market acceptance of new products, which is conducive to the improvement of new product development performance. (2) While the relationship between complementary technology convergence and new product development performance of firms presents a U-shaped one. This is because in the early stages of R&D, enterprises can greatly promote the emergence of new technologies and develop more new products by introducing advanced technologies in other fields that are highly complementary with their own technologies. However, in the later stage of commercialization, the demand information in different fields may be distributed in different enterprises, the realization of complementary technical knowledge integration and product optimization by enterprises will generate more and more time-consuming coordination costs and conversion costs, which is not conducive to the further increase of new product development performance.

Some scholars believe that the emergence of different types of technologies in the same patent reflects the correlation of technologies, which reveals the fusion of technologies between different industries. Based on the characteristics of technology combination relationship, this paper divides technology convergence into two types: complementary technology convergence and substitution technology convergence and empirically analyzes the influence of these two different technology convergence methods on the performance of new product development of enterprises. Therefore, on the one hand, the innovation of the measurement method of the convergence of complementary and substitution technologies is realized in theory, which provides a quantitative prediction tool for the technological evolution of enterprises. On the other hand, it provides new ideas for enterprises to effectively carry out cross-field technology integration strategy, improve the performance of new product development and accelerate the pace of industrial transformation and upgrading. 

However, due to the difficulties in data collection, this paper also has some limitations. (1) Patent data is an important way to identify the phenomenon of technologies intersection and the technological evolution. In this paper, only the patent′ IPC analysis method is used, and the subsequent research can incorporate the patent citation analysis method and the patent′ IPC analysis method into the technology convergence analysis framework, and provide a more accurate predictive tool for the comprehensive investigation of the cross-domain technology convergence and its dynamic evolution. (2) In this paper, a single sample data of the new energy vehicle industry is used to analyze the research. In this paper, a single sample data of the new energy vehicle industry is used to analyze the research problems. The subsequent research can be upgraded to the industrial level, and a comparative analysis is carried out in combination with a number of different industries, so as to provide more general suggestions for enterprises to construct a reasonable technological development path. 

complementarity technology convergence, substitution technology convergence, new product development performance, green-power automobile enterprise