Phenothiazine-Based Hole Transport Materials for Perovskite Solar Cells

Abstract

The promising photovoltaic solar cells based on the perovskite light-harvesting materials have attracted researchers with their outstanding power conversion efficiencies (over 23% certified). The perovskite work has geared up in just under a decade and is competing with well-established semiconductor technologies such as silicon (Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). To commercialize the perovskite solar cells, their stability is the major concern. To address the stability issue, several factors need to be taken into account, and one of them is developing stable hole transport materials (HTMs), which are the essential building blocks. In this mini-review, we will discuss the important features of the HTMs, such as design and development of phenothiazine-based HTMs. Since phenothiazine is a low cost and stable molecule compared to the spiro-OMeTAD, it can be modified further via molecular engineering.

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

“…This observation showed, that the weight loss of these compounds apparently was due to sublimation. The carbon residue of compound 3 was attributed to the tendency of the phenothiazine moiety to decompose rather than to sublimate, as it has been observed for similar phenothiazine-based compounds [15].…”

Mechanisms and Suppression of Photoinduced Degradation in Perovskite Solar Cells

“…Molecular engineering can suppress the crystal growth to some extent. [256,257] Developing new HTMs, such as the thiophene derivatives, silolothiophene linked methoxy triphenylamines can also inhibit the crystallization. [258,259]…”

Structure-induced optoelectronic properties of phenothiazine-based materials

“…PTZ-Based HTMs are of particular interest, because, besides the aforementioned optoelectronic properties in Section 2, they can be synthesized through simple and cheap procedures, offering a viable alternative to the commonly used but extremely expensive 2,2 0 ,7,7 0 -tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9 0spirobifluorene (spiro-OMeTAD). 23 Further, multiple functional sites of the PTZ moiety offer the feasibility of using it either as core or as peripheral unit and scope for further functionalization, improving the charge transporting materials. This provides a great advantage compared to other compounds, it is indeed known that small differences in structure can lead to big changes in behaviour.…”

“…22 Exploiting these features, several small molecules and polymers have been designed and synthesized and successfully applied as photoactive materials in organic electronic devices, such as organic light-emitting diodes (OLEDs), organic fieldeffect transistors (OFETs), dye-sensitized solar cells (DSSCs), organic solar cells (OSCs), perovskite solar cells (PSCs), batteries, sensors, and others. [23][24][25][26] While the key optoelectronic applications of PTZs, especially related to solar cells, are already reviewed in several good papers, [23][24][25][26] a comprehensive overview of the use of PTZ chromophores in optoelectronics, with special emphasis on the chemistry of the materials and their structure-propertydevice performance relationships is not yet thoroughly reported.…”