Donor–Acceptor Type Polymer Bearing Carbazole Side Chain for Efficient Dopant-Free Perovskite Solar Cells

Abstract Costs and toxicity concerns are at the center of a heated debate regarding the implementation of perovskite solar cells (PSCs) into commercial products. The first bottleneck could be overcome by eliminating the top metal electrode (generally gold) and the underlying hole transporting material and substituting both with one single thick layer of conductive carbon, as in the so‐called carbon‐based PSCs (C‐PSCs). The second issue, related to the presence of lead, can be tackled by resorting to other perovskite structures based on less toxic metallic components. An interesting case is that of the double perovskite Cs2AgBiBr6, which at present still lacks the outstanding optoelectronic performances of the lead‐based counterparts but is very stable to environmental factors. In this work, the processing of carbon electrodes onto Cs2AgBiBr6‐based C‐PSCs was reported, starting from an additive‐free isopropanol ink of a carbon material obtained from the hydrothermal recycling of waste tires and employing a high‐throughput ultrasonic spray coating method in normal environmental conditions. Through this highly sustainable approach that ensures a valuable step from an end‐of‐life to an end‐of‐waste status for used tires, devices were obtained delivering a record open circuit voltage of 1.293 V, which might in the future represent ultra‐cheap solutions to power the indoor Internet of Things ecosystem.

High Open‐Circuit Voltage Cs2AgBiBr6 Carbon‐Based Perovskite Solar Cells via Green Processing of Ultrasonic Spray‐Coated Carbon Electrodes from Waste Tire Sources

Perovskite solar cells enhancement by CZTS based hole transport layer

Perovskite solar cells (PSCs) have become a hot spot in the field of photovoltaic research in recent years due to their low fabrication costs and rising efficiencies. However, the performance and stability degradation caused by defect states in metal halide perovskites are the main constraint to the development of PSCs. At present, researchers have successfully designed and synthesized a series of organic hole transport materials (HTMs) with excellent passivation function by introducing passivation functional groups into the structure of HTMs to passivate the defects in perovskite films, effectively improving the performance and stability of PSCs. Herein, we review the recent progress of organic HTMs with defect passivation function for efficient and stable PSCs. We mainly introduce some representative organic HTMs with passivation function, summarize and comment on their photovoltaic parameters, and explore the effect of passivation groups on their performance. Finally, we provide a guideline for the future design of novel and efficient HTMs with defect passivation based on current research. 

Surface passivation of perovskite with organic hole transport materials for highly efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) have undergone unprecedented growth in the past decade as an emerging photovoltaic technology. Up till now, the power conversion efficiency of PSCs has exceeded 25% that rivals silicon solar cells and there is still room for further enhancement. However, the development in long‐term stability lags far behind, which remains a great concern for the commercial application in the future. The device instability mainly arises from the functional components, including perovskite film, charge transport layers, and electrodes along with the involved interfaces. As the most widely studied hole transport layer at the current stage, 2,2′,7,7′‐tetrakis(N,N‐di(4‐methoxyphenyl)amino)‐9,9‐spirobifluorene (Spiro‐OMeTAD) helps contribute to the achievement of record efficiency but it weakens the device stability due to the doping‐induced side effects such as hygroscopicity and ion migration. Great efforts are devoted to boosting the stability of Spiro‐OMeTAD while maintaining excellent photovoltaic performance. In this review, the fundamental properties of Spiro‐OMeTAD have been summarized and the recent advances in engineering Spiro‐OMeTAD‐based hole transport layer for the sake of highly efficient PSCs with enhanced longevity are highlighted. In the end, an outlook for the further optimization of Spiro‐OMeTAD is provided and the issues related to large‐scale production are discussed.

Spiro‐OMeTAD‐Based Hole Transport Layer Engineering toward Stable Perovskite Solar Cells

https://onlinelibrary.wiley.com/doi/pdf/10.1002/solr.202100514

Wei Chen

Papers

The Non-Innocent Role of Hole-Transporting Materials in Perovskite Solar Cells