Recent Progresses on Dopant‐Free Organic Hole Transport Materials toward Efficient and Stable Perovskite Solar Cells^†

Abstract

Comprehensive SummaryAs the third generation new battery, the power conversion efficiency (PCE) of metal halide perovskite solar cells (PSCs) have increased from 3.8% in 2009 to 25.8% currently certified, which fully show that they have great research value and development prospect. As one of the main components of high‐efficiency PSCs, hole transport materials (HTMs) play an important role in extracting and transporting holes and inhibiting charge recombination. However, commonly used HTMs require doping, and the hygroscopicity and corrosiveness of the dopants will destroy the stability of PSCs and hinder their commercialization. Therefore, it is of great significance to develop dopant‐free HTMs. In this review, the dopant‐free HTMs in recent six years are reviewed and summarized systematically, including organic small molecules, polymers and cross‐linkable materials. We focus on the design of the molecular cores and discuss their structure–property correlation, conductivity, and photovoltaic performance. Finally, how to design an ideal HTM is summarized. We hope that this review can provide reference for the development of low‐cost and dopant‐free HTMs to prepare efficient and stable PSCs.This article is protected by copyright. All rights reserved.

Dual‐Strategy Tailoring Molecular Structures of Dopant‐Free Hole Transport Materials for Efficient and Stable Perovskite Solar Cells

“…The integrated photocurrent densities obtained from the external quantum efficiency (EQE) curves were 23.5, 24.0 and 24.2 mA cm −2 for DTTP‐ThC6, DTTP‐ThSO and Spiro‐OMeTAD based devices, respectively, which were well in agreement with the measured J sc values (Figure 6c). To the best of our knowledge, the PCE, especially the FF are among the highest values for the dopant‐free small molecular/polymeric HTMs‐based n‐i‐p PSCs reported so far (Figure 6d, Table S5) [6a] …”

A review on conventional perovskite solar cells with organic dopant-free hole-transport materials: roles of chemical structures and interfacial materials in efficient devices

“…46–48 Recently, several reviews concerning organic dopant-free HTMs have been published, and the structure–property correlation has been well documented. 49–51 Generally, it is believed that the HTMs with deep highest occupied molecular orbital (HOMO) energy levels and high hole mobility contribute to open-circuit voltage ( V OC ), short-circuit current density ( J SC ) and fill factor (FF), respectively. However, it was found that there is not strong relationship between these two material properties and the photovoltaic parameters of devices (Fig.…”

Non‐Equivalent Donor‐Acceptor Type Polymers as Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

“…[15][16][17][18][19] Conjugated polymers (CPs) have long-range conjugation chains, benefiting carriers transport through the intermolecular jump and intra-molecular transfers to obtain high hole mobility without doping. [20][21][22][23][24] Electron donor (D)-electron acceptor (A) type CPs are the promising candidates as dopant-free HTMs for PVSCs, [25] due to their intermolecular and intramolecular chargetransfers (ICT). [26][27][28] The current study on D-A polymeric HTMs focuses on the chemical modification of D and A units in substituents, [29,30] π-bridge, [31] and conjugated rings.…”