Hybrid perovskite semiconductors are an emerging family of materials with exceptional optoelectronic properties. Solar cells of these materials have shown power conversion efficiencies greater than 25 %, light emitting diodes with external quantum efficiency >20 % and continuous wave lasers with a low lasing threshold of 6 μJ/cm2. The ‘PHOTOPEROVSKITES’ is Lethy Krishnan Jagadamma’s Marie Curie Individual Fellowship project under the supervision of Professor Ifor Samuel, funded by HORIZON 2020, European Commission [2017 September to Feb 2020].

Research Programme

The main tasks involved in the fellowship programme are:

  1. To investigate the time-resolved spectroscopic characterization of thin film perovskite solar cells
  1. To determine the role of crystalline grain size and grain boundaries in photophysics and photovoltaic properties of perovskite solar cells
  1. To develop low temperature solution-processed metal oxide interfacial charge transport layers for efficient perovskite solar cells



Publications from the PHOTOPEROVSKITES project include:

  1. Efficient indoor p-i-n hybrid perovskite solar cells using low temperature solution processed NiO as hole extraction layers

    Lethy Krishnan Jagadamma
    , Oskar Blaszczyk, Muhammad T. Sajjad, Arvydas Ruseckas, Ifor D. W. Samuel; Solar Energy Materials & Solar Cells 2019 201 110071

    We have demonstrated a low temperature (~100 °C) solution – processed and ultrathin (~6 nm) NiO nanoparticle thin films as an efficient hole extraction layers (HEL) for CH3NH3PbI3 based perovskite solar cells. We measured a power conversion efficiency (PCE) of 13.3% on rigid glass substrates and 9% on flexible substrates. Apart from the photovoltaic performance under 1 Sun, the efficient hole extraction property of NiO was demonstrated for indoor lighting as well with a PCE of 23.0% for NiO based CH3NH3PbI2.9Cl0.1 p-i-n solar cells under compact fluorescent lighting. Compared to the perovskite solar cells fabricated on PEDOT:PSS HEL, better shelf-life stability is observed for perovskite solar cells fabricated on NiO HEL. 

  2. Interface limited hole extraction from methylammonium lead iodide films
    Oskar Blaszczyk, Lethy Krishnan Jagadamma, Arvydas Ruseckas, Muhammad T. Sajjad, Yiwei Zhang, Ifor D. W. Samuel; Mater. Horiz. 2020, 7, 943
    DOI: 10.1039/C9MH01517E 

    We presented a method to unambiguously distinguish between bulk and interface effects on charge extraction dynamics which is based on time-resolved photoluminescence with different excitation density profiles. We used this method to study charge extraction from solution-deposited CH3NH3PbI3 films to NiO and PEDOT:PSS layers. We found that NiO shows faster hole extraction than PEDOT:PSS from the 300 nm thick perovskite film on the time scale of 300 ps which is independent of charge carrier density in the region of 1016–1017 cm−3. This was in contrast to PEDOT:PSS where we found the charge extraction rate to be slower, decreasing with time and dependent on charge density in the region 1016–1017 cm−3 which we interpreted as charge accumulation at the interface. Hence we found that charge extraction was severely limited by the interface with PEDOT:PSS.