Progress in three‐terminal heterojunction bipolar transistor solar cells

Abstract

Abstract Conventional solar cells, including multijunction solar cells, are based on pn junctions as building blocks. In contrast, the three‐terminal heterojunction bipolar transistor solar cell (3T‐HBTSC) explores the use of a bipolar transistor structure to build a solar cell. The limiting efficiency of this transistor structure equals that of a double‐junction solar cell. However, since the 3T‐HBTSC does not require tunnel junctions, its minimal structure has only three semiconductor layers, while the minimal structure of a double junction solar cell has six. This work reviews the operation principles of this solar cell and the steps carried out towards its practical implementation. Experimental results on a GaInP/GaAs HBTSC prototype with bottom interdigitated contacts are presented.