(Fig 1. Fabricated ~23% efficient silicon heterojunction solar cell with parameters)

The Solar Photovoltaics group from the Dept. of Energy Science and Engineering at IIT Delhi, with the responsibility of harnessing solar energy directly into electrical energy efficiently with minimal impact on the Environment, has been working on developing high-efficiency silicon heterojunction (SHJ) solar cells. Recently, the group has reached a power conversion efficiency of >23% for SHJ solar cells of 4 cm² area (shown in Fig. 1) with better know-how, experience, and innovation. A pleasing milestone is the achievement of a high fill factor (~81%) and voltage (~735 mV) in cells.

The main advantages of SHJ solar cell technology are that it performs better at relatively high temperatures with high power output compared to other silicon-based solar cell technologies, cells can be fabricated at low temperatures with simple process steps and light can be absorbed from both sides.

(Fig 2. Systems used for fabricating silicon heterojunction solar cell)

IIT Delhi researchers’ SHJ solar cell project began with a modest collaboration with BHEL India, and after that, they started working on an indigenous developed PECVD system initially followed by state of the art system in the lab. Throughout, the researchers consistently observed advancements in cell efficiency from ~8% to ~23%.

“Attaining such high efficiency from an SHJ cell for the first time in Indian conditions is a challenging job. While we still trail behind the international research laboratory efficiency benchmark of >24% of SHJ cells in small areas, we have now identified methods to enhance efficiency further”, said Prof. Vamsi Krishna Komarala, Dept. of Energy Science and Engineering, IIT Delhi.

This accomplishment results from years of dedicated effort from several students and post-doctoral researchers with more than 15 high-impact publications and 3 patents, many of whom have since moved on to various international/national industries and institutions. Significant contributions came from the group members, Dr. Son Pal Singh, Dr. Sourav Mandal, Dr. Ashutosh Pandey, Ms. Shrestha Bhattacharya, Dr. Jagannath Panigrahi, Mr. Shahnawaz Alam, Mr. Silajit Manna, Ms. Honey Sharma, Ms. Manisha, and a group led by Prof. Vamsi Krishna Komarala. The Solar Photovoltaics group has received initial support from the Institute of Eminence grant, well-established Central and Nanoscale Research Facilities for characterization and clean room for device fabrication from IIT Delhi, followed by the Solar Challenge Award grant with substantial financial support from the Technology Mission Division of the Department of Science and Technology (DST), Govt. of India under Climate, Energy and Sustainable Technologies (CEST) division.

The IIT Delhi research group is now also making efforts in the lab for industrial-size silicon heterojunction solar cell fabrication.

Research paper links: DoIs: https://doi.org/10.1007/s10854-025-14573-w, https://doi.org/10.1021/acsaem.4c02475

(Fig 3: Solar Photovoltaics Group from the Dept. of Energy Science and Engineering at IIT Delhi)