While the efficiency of methylammonium lead trihalide(MAPbX3) perovskite is approaching the limit and other issues are raised, increasing attention is quietly placed on formanidinium lead trihalide(FAPbX3), which is especially highlighted in the H.J. Snaith and N.-G. Park's talks in the MRS spring 2014.

The reduced bandgap of ~1.47eV, enhanced thermal stablity (suggested by Snaith group), less hysteresis (suggested by Park) are making FAPbI3 a growing "star".

Copyright@ S.Pang,et al. Chem. Mater. 2014, 26, 1485−1491

While it seems new to the audience, it has been explored by a couple of groups. It is noteworthy that a chinese group is involved in initializing this important perovskite solar cell research.

Singapore Group (NTU) published the first paper (JPCC) on applying FAPbI3 into mesoscopic solar cells. However, they were not able to obtain pure phase when incorporating the FAPbI3 into meso-TiO2 due to formation of non-perovskite phase. Nevertheless, it is very respectable and valuable for the first report on FAPbI3.

http://pubs.acs.org/doi/abs/10.1021/jp411112k  

S. Pang Group from Qingdao Institute of Bioenergy and Bioprocess Technology, CAS reported a parallel research on the same topic in Chem.Mater.. They succefully suppressed the non-perovskite FAPbI3 formation and synthesized pure FAPbI3 perovksite using both one-step and two-step methods. The perovksite is also well characterized and more reliable results are present due to the better crystal quality.

http://pubs.acs.org/doi/abs/10.1021/cm404006p  

H.J. Snaith Group also published their work on FAPbI3 (EES), but applied to planar structured solar cell, a maximium PCE of 14.3 % was obtained, which is the record for the pure one-step solution processed solar cell. This paper also includes FAPbI3-xBrx band tuning and diffusion length characterization.

http://pubs.rsc.org/en/Content/ArticleLanding/2014/EE/C3EE43822H#!divAbstract  

The above three papers are considered in parallel and thus some repeated comments are appearing in the three papers.

Gratzel Group later published mixed-organic-cation perovskite study, in which they are able to promote the PCE by partially replacing the MA cation with FA cation.

http://onlinelibrary.wiley.com/doi/10.1002/anie.201309361/abstract  

Also, Kanazadis Group from Northwestern University firstly reported a comprehensive material research on FAPbI3 in a massive research paper on Inorg. Chem..

http://pubs.acs.org/doi/abs/10.1021/ic401215x