**6. Conclusions**

In this chapter, we presented the ability of OIHP materials including organic and inorganic halide perovskite materials to produce electricity by harvesting the ambient abundant mechanical energy. The structural suitability of various OIHPs and OIHP– polymer composites for developing high-performance MEHs is discussed in detail along with their dielectric, piezoelectric, and ferroelectric properties. In addition, some significant works based on OIHP-MEHs in the form of PENGs and TENGs are summarized. Finally, the existing issues and challenges facing current research are stated and some future research directions for pursuing the commercialization of OIHP-based MEHs in wearable, portable electronic devices are suggested.

### **Acknowledgements**

This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2021R1A2B5B03002016, NRF-2021R1A2C1010797, NRF-2021R1I1A1A01060012) and by the Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant No. 2021R1A6A1A03043682).

## **Conflict of interest**

The authors declare no conflict of interest.

## **Author details**

Venkatraju Jella\*† , Swathi Ippili\*† , Hyun You Kim, Hyun-Suk Kim, Chunjoong Kim, Tae-Youl Yang and Soon-Gil Yoon\* Department of Materials Science and Engineering, Chungnam National University, Daejeon, Republic of Korea

\*Address all correspondence to: venkatrajujella@gmail.com, iswathirs@gmail.com and sgyoon@cnu.ac.kr

† Both authors contributed equally to this work.

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