Research progress of crystalline silicon solar cells with dopant-free asymmetric heterocontacts

Abstract

Due to the rapid development of dopant free asymmetric heterogeneous contacts in recent years, the theoretical conversion efficiency can reach 28%, which has large room for development and has attracted one’s attention. With the expectation of low cost and green pollution-free solar cell, the traditional crystalline silicon solar cell has many limitations due to its high equipment cost and flammable and explosive raw materials. It greatly increases the necessity of research and development of new solar cells with no doping and asymmetric heterogeneous contacts. The new solar cell is safe and environmental friendly due to the multi-faceted advantages of dopant-free asymmetric heterogeneous contact (DASH) solar cells constructed by transition metal oxide (TMO): the TMO has been widely studied as an alternative option, because of its wide band gap, little parasitic absorption, as well as repressed auger recombination, and conducing to the increase of the short-circuit current density of the solar cells; the DASH solar cell has high efficiency potential, its theoretical efficiency has reached 28%, and it can be produced by low-cost technology such as thermal evaporation or solution method; it always avoids using flammable, explosive and toxic gases in the manufacturing process. Our group proposed using MoO<sub><i>x</i></sub> as a hole selective contact and ZnO as an electron selective contact to construct a new and efficient DASH solar cell. It has achieved a conversion efficiency of 16.6%. Another device, in which MoO<sub><i>x</i></sub> is used as the hole selective contact and n-nc-Si:H as the electron selective, was fabricated, and its efficiency has reached 14.4%. In order to further speed up the research progress of the dopant-free asymmetric heterogeneous contact crystalline silicon solar cell, the development status is reviewed, and the basic principle and preparation technology of selective transport of transition metal oxide (TMO) carriers are discussed. And the effect of the hole transport layer, the electron transport layer and the passivation layer on the performance of the TMO dopant-free asymmetric heterogeneous contact (DASH) solar cells are discussed in order to have an in-depth understanding of the working mechanism and material selection of the battery, thereby providing guidance in preparing new and efficient DASH solar cells.