$$PVDG$$ Crazy if I can find the r A company that uses or develops this further I'll let you know. Haven't been able to track them down yet. As far as investing at least.
Panasonic, the manufacturer of the HIT® high-performance modules, is among the small number of producers already offering heterojunction cells and committing to this technology. Now, for the first time, Panasonic explains how the higher efficiency is achieved and what goals the company has in cell development.
Turning first to the technology behind solar cells. How do heterojunction cells differ from other solar cells, especially well-established crystalline and thin-film cells? https://eu-solar.panasonic.net/en/3070.htm
II. Past and Future The first heterojunction device was reported in 1983 with efficiency over 12% [2]. In the early 1990’s Sanyo (recently acquired by Panasonic) developed their own design, the HIT® solar cell (Heterojunction with Intrinsic Thin-layer). Sanyo introduced a thin intrinsic a-Si buffer layer between the doped emitter and the substrate drastically reducing the recombination at the surface [3]. Recently, Kaneka Corporation achieved an efficiency 26.7 % for 79 cm2 solar cell, which is the current world-record silicon solar cell [4]. To maximize the short-circuit current, all the contacts were placed on the back of the cell. This result is getting very close to the fundamental one-Sun limit of ~29% for single junction silicon solar cells. [5]