Hybrid perovskites for indoor photovoltaic applications

Abstract

This thesis focuses on developing efficient indoor perovskite photovoltaic device in terms of device architecture, perovskite active layer, and charge transport layers. Indoor photovoltaics are receiving tremendous attention due to the continuous development of the Internet of Things. This thesis investigates the device performance and optoelectronic properties of perovskite thin films and corresponding devices with assist of various characterisations.

The device performances are highly dependent on the architecture of devices due to different types of transport layers. How the selection of hole extraction layers (HELs) impacts the device performance is studied. For n-i-p device, The Spiro-OMeTAD-based devices show a consistently higher power conversion efficiency with fewer trap states and higher carrier lifetime compared to P3HT. For p-i-n devices, We found that the metal oxide HEL (NiO and CuOx) based devices suffer severe light soaking effects and the bulk vs interface traps contribution to the detrimental light soaking effects. Interface modification of metal oxide transport layers using 2PACz eliminated the light-soaking effects, passivated the defects, suppressed the leakage current.

The thesis reports how the fast processing of the triple halide perovskite enables the retention of chlorine and the beneficial role of chlorine in enhancing the indoor light harvesting of a wide bandgap triple anion (TA) perovskite CH₃NH₃PbI₂.₆Br₀.₂Cl₀.₂. The best-performing TA perovskite indoor-photovoltaic device achieved a steady-state power conversion efficiency (PCE) of 25.1% with an output power density of ∼75 μW cm⁻² under 1000 lux indoor illumination (0.3 mW cm⁻²). Improved crystalline quality, reduced defect density and longer carrier lifetime were achieved.

Efforts are taken to realise the vision of IoT. This thesis successfully achieved photovoltaic sensor powering by direction connection, real-time monitoring, and independent power management. The results from the thesis demonstrate novel routes to develop efficient and reliable indoor photovoltaics and the potential to integrate the device with microelectronic sensors.