High‐Performance and Stable Dopant‐Free Silicon Solar Cells with Magnesium Acetylacetonate Electron‐Selective Contacts

Abstract

One of the challenges in fabricating high‐performance n‐type crystalline silicon (n‐type c‐Si) solar cells is the high‐quality n‐type c‐Si/metal contact. Schottky barriers are commonly found on the n‐type c‐Si/metal contact, which suppresses electron transportation. Herein, novel stacks of magnesium acetylacetonate (Mg(Acac)2)/magnesium (Mg)/silver (Ag) to form electron‐selective contacts for n‐type c‐Si solar cells are presented, which enables a dopant‐free process. An ohmic contact on n‐type c‐Si is formed using the Mg(Acac)2/Mg/Ag stacks. The transmission spectrum and ultraviolet photoelectron spectroscopy measurements show negligible conduction‐band offset and large valence‐band offset between Mg(Acac)2 and n‐type c‐Si, which indicates the electron‐transporting and hole‐blocking properties of Mg(Acac)2/n‐type c‐Si heterocontacts. Moreover, the contact resistivities (ρc) between the Mg(Acac)2/Mg/Ag electron‐selective heterocontacts and n‐type c‐Si substrates are lower than 10 mΩ cm2, which demonstrates the good electrode properties of the Mg(Acac)2/Mg/Ag stacks. The Mg(Acac)2/Mg/Ag electron‐selective stacks are applied on n‐type c‐Si solar cells with partial rear contact, and >20% efficiency is achieved, which is higher than that in a reference cell with only Ag contact. The stability of the n‐type c‐Si solar cell performance equipped with Mg(Acac)2/Mg/Ag contacts is verified under ambient conditions. This novel low‐temperature contact technique offers a reliable alternative for high‐performance n‐type c‐Si solar cells.

Highly Stable Strontium Fluoride as a Thickness Tolerant Electron‐Selective Contact for Dopant‐Free Silicon Solar Cells

“…DF-ECSCs works in kinds of literature report that the minimum ρ c can be achieved by EuF x (15.6 mΩ•cm 2 ), YF 3 (17.8 mΩ•cm 2 ), MgO x (17.5 mΩ•cm 2 ), CeF 3 (10.96 mΩ•cm 2 ), MgAcac (7.6 mΩ•cm 2 ), MgF x (35 mΩ•cm 2 ), TiO 2 (20 mΩ•cm 2 ), TaN x (42 mΩ•cm 2 ) prepared by thermal evaporation or by atomic layer deposition (ALD). 11,[18][19][20]22,26,36,37 And the value of ρ c resembles the most typical material LiF x (1 mΩ•cm 2 ). 7 However, lithium fluoride is toxic and harmful to human health and the environment, and Li resources and its compounds are in short supply on Earth, which is not conducive to large-scale applications.…”

The Investigation of Photovoltaic and Electrical Properties of Bi Doped CTS/Si Hetero-Junction Structure for the Solar Cell Application

“…Al back contact (4.06 eV) tends to exhibit ohmic behaviour for n-Si (4.58 eV) semiconductors. Thus, charge flow can be easily achieved through the contact and a contribution to charge collection can be made [45][46][47]. As a result, Ag/Bi doped CTS/n-Si/Al hetero-junction shows the photovoltaic property and the higher efficiency can be achieved in CTS thin film solar cells with the improvement studies on CTS and Bi doped CTS thin film.…”

Temperature and environmentally stable titanium carbide as an electron-selective heterocontact for crystalline silicon solar cells

“…Recently, transition metal oxides (TMOs) and alkali metal fluorides have been widely investigated as electron-selective contact (ESC) materials, forming excellent Ohmic contacts to the lightly doped n-type c-Si with mΩ cm 2 scale contact resistivities. 8–38 The studies of ESC materials have further extended to low-work-function alkali or alkaline earth metals, 39,40 transition metals, 22 and their compounds such as halides, 36,41 oxides, 14,42,43 nitrides, 28,29 sulfides, 30,44 silicides, 45 carbonates 46 as well as organic compounds. 47,48 As a result, c-Si solar cells with dopant-free ESC have exhibited a high conversion efficiency beyond 23%.…”