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

Abstract

Hybrid perovskites have received tremendous attention due to their exceptional photovoltaic and optoelectronic properties. Among the two widely used perovskite solar cell device architectures of n-ip and p-i-n, the latter is interesting in terms of its simplicity of fabrication and lower energy input. However this structure mostly uses PEDOT:PSS as a hole transporting layer which can accelerate the perovskite solar cell degradation. Hence the development of stable, inorganic hole extraction layers (HEL), without compromising the simplicity of device fabrication is crucial in this fast-growing photovoltaic field. Here we demonstrate a low temperature (~100 o C) solution -processed and ultrathin (~ 6 nm) NiO nanoparticle thin films as an efficient HEL for CH3NH3PbI3 based perovskite solar cells. We measure a power conversion efficiency (PCE) of 13.3 % on rigid glass substrates and 8.5 % on flexible substrates. A comparison with PEDOT:PSS based MAPbI3 solar cells (PCE ~ 7.9 %) shows that NiO based solar cells have higher short circuit current density and improved open circuit voltage (1.03V). Apart from the photovoltaic performance under 1 Sun, the efficient hole extraction property of NiO is 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. Detailed microstructural and photophysical investigations imply uniform morphology, lower recombination losses, and improved charge transfer properties for CH3NH3PbI3 grown on NiO HEL.

Interface limited hole extraction from methylammonium lead iodide films

“…The simplicity of fabrication, low processing temperature and compatibility with roll-to-roll manufacturing processes make this an attractive solar cell architecture but it suffers problems with efficiency and stability, partly due to its acidity, temperature sensitivity and hygroscopic properties. 10 A low processing temperature and stable hole transporting layer based on NiO nanoparticles has been proposed as a superior HEL recently by Jagadamma et al 11 but it is still unclear what the underlying reasons for improved charge extraction from the solar cell are and what role charge transport and interfacial transfer rate play in charge extraction, making it very difficult to compare between different charge extracting materials even for the same perovskite composition and preparation method. This information is crucial when aiming to develop solar cells with hot carrier extraction which potentially can break the Shockley-Queisser limit.…”

Indoor application of emerging photovoltaics—progress, challenges and perspectives

“…Jagadamma et al developed an ultrathin HTL based on solution-processed NiO nanoparticles instead of PEDOT:PSS for indoor PPV devices, achieving a PCE of 23% under compact uorescent lighting (0.32 mW cm À2 ). 105 Aer 3.7 months under ambient air conditions (in the dark, RH $ 40%), the perovskite layer on the NiO HTL still retained its initial black-brown colour while the ones on PEDOT:PSS turned yellowish implying a severe loss of absorbance. The above mentioned (in Section 2.2.1) SnO 2 /MgO 55 and PCBM/[BMIM]BF 4 (ref.…”

Solar Cells for Indoor Applications: Progress and Development

“…In addition to the development of different semiconducting materials for ETLs, some researchers have attempted to improve the performance of PVSCs for indoor applications through the development of different p-type semiconducting materials as HTLs. For example, Jagadamma et al developed an efficient p-i-n hybrid indoor PVSC by using NiO as the HTL [ 118 ]. Their device exhibited a PCE of 23% under the illumination of a fluorescent lamp having an irradiance power intensity of 0.32 mW/cm 2 .…”