Use of carbon as counter electrode in cheap and stable perovskite solar cells

• Grant number: 23/14502-0
• Support Opportunities: Scholarships in Brazil - Program to Stimulate Scientific Vocations
• Start date: February 01, 2024
• End date: March 20, 2024
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Ana Flávia Nogueira
• Grantee: Islaine Elí Lima Gomes
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Perovskite solar cells (PSCs) represent a promising photovoltaic technology, due to the advantages related to their excellent optoelectronic properties, and above all, the rapid increase in power conversion efficiency (PCE), from 3.9% (2009) to 26.1% ( 2023). Furthermore, these devices have several facilities in their manufacturing process, since all layers can be processed via solution using scalable deposition techniques. However, n-i-p type PSCs (Glass/FTO/ETL/Perovskite/HTL/Au) have presented some problems related to their stability and manufacturing cost, especially the use of the gold (Au) counter electrode and Spiro-OMeTAD ( 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene) as hole transport layer (HTL). Both gold and Spiro-OMeTAD are high-cost materials. The deposition of the gold counter electrode is done using sophisticated techniques, such as the thermal evaporation process under high vacuum. The synthesis of Spiro-OMeTAD requires multiple steps and an expensive sublimation step for purification. Therefore, both the use of gold and Spiro-OMeTAD make PSCs unattractive and commercially unviable. One of the solutions found has been the use of carbon-based materials (CMs), which are abundant, cheap, hydrophobic (and therefore more robust under environmental conditions), have a work function (5.0 eV) close to work function of gold (5.1 eV) and do not require the use of a hole transport layer. Another advantage is that MCs are easy to deposition, which makes it possible to use deposition techniques such as foil-coating and screen printing, for example, which are low-cost and, above all, scalable methods. In this context, this scientific vocations project was prepared with the objective of manufacturing large-scale PSCs (active area of 1 cm2), low cost and stable, replacing the gold electrode with carbon (deposited by the blade-coating technique) and without the use of HTL. (AU)