Dopant Engineering for Spiro‐OMeTAD Hole‐Transporting Materials towards Efficient Perovskite Solar Cells

Abstract

One of the most prominent hole‐transporting material (HTM) for hybrid perovskite solar cells has been 2,2″,7,7″‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐OMeTAD), which is commonly doped with metal bis(trifluoromethylsulfonyl)imide (M(TFSI)n) salts that contribute to generating the active radical cation HTM species. The underlying role of the metal cation, however, remains elusive. Here, the effect of metal cations (M = Li, Zn, Ca, Cu, and Sc) on doping spiro‐OMeTAD is analyzed by a combination of techniques, including electron paramagnetic resonance spectroscopy and cyclic voltammetry, which is complemented by photovoltaic device and hole mobility analysis. As a result, the authors reveal the superiority of Zn(TFSI)2 salts in device performances as compared to the others, including redox‐active Cu(TFSI)2. This analysis thereby unravels new design principles for dopant engineering in HTMs for hybrid perovskite photovoltaics.

Oxidized Spiro-OMeTAD: Investigation of Stability in Contact with Various Perovskite Compositions

“…In the broader context of research performed recently addressing stability issues, at the first glance, results reported in this publication would seem to contradict them. However, if we look at the device stability curves presented in the research articles describing PSCs containing doped spiro-OMeTAD, for example, Christians et al, 44 Seo et al, 45 and Kong et al, 46 there is a slow but consistent decrease in device performance. This drop in performance can be attributed to more than one factor; however, it does not eliminate the prospect that processes described in this publication are also playing a role.…”

Strategies for high‐performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

“…It is attributed to more fluorine content in LiPFSI, which not only increases hole extraction/transfer and improves film-forming capability of spiro-OMeTAD, but also reduces the recombination rate and trap density in the perovskite film. Except for lithium salt, other metal salts have been employed to improve the properties of spiro-OMeTAD and its HPSCs, such as AgTFSI, 518 Zn (TFSI) 2 , [519][520][521] Ca(TFSI) 2 , 519,522 Cu(TFSI) 2 , 519,523 MgTFSI 2 , 522 and Sc(TFSI) 3 . 519 The second kind of additives is the organic material, such as tBP, 524,525 PFPPY, 526 BMPyTFSI, 527 and pyridine.…”

SnO2 Elektron Transfer Tabakasının Slot-Die Tekniği ile Üretimi ve Optimizasyonu

“…Özellikle son yıllarda oldukça popüler bir araştırma alanı olan perovskite güneş hücrelerinin slot-die tekniği ile üretimi literatürde önemli bir yer tutmaktadır. Bilindiği gibi perovskite güneş hücreleri alttaş, elektron transfer tabakası, aktif soğurucu tabaka, boşluk transfer tabakası ve metal üst elektrot olmak üzere farklı tabakaların sandviç modelinde bir araya getirilmesi ile oluşmaktadır [38][39][40]. Bu tabakalardan elektron transfer tabakası perovskite hücre teknolojisinde aygıt performansı üzerinde önemli bir etkiye ve fonksiyona sahiptir.…”