Conductive polymer doped carbon electrode for high-performance hole transport layer free perovskite photovoltaics and self-powered photodetectors

Abstract

Carbon-based perovskite optoelectronic devices without a hole transport layer (HTL) offer significant advantages, including simplified fabrication, low cost, and excellent stability, positioning them as highly promising candidates for optoelectronic applications. However, the direct contact between carbon electrodes and the perovskite layer leads to substantial non-radiative recombination losses at the interface, limiting their performance compared to devices incorporating HTLs. Herein, we incorporate polypyrrole (PPy), a conductive polymer with defect passivation capabilities, into the carbon paste to fabricate HTL-free carbon electrode perovskite solar cells. PPy not only passivates surface defects in the perovskite but also facilitates hole transport, thereby enhancing the hole collection efficiency of the carbon electrodes. As a result, the power conversion efficiency (PCE) of the HTL-free carbon-based perovskite solar cells (C-PSCs) achieved 18.48%, with an indoor efficiency of 26.74% at 2000 lux. These values represent superior performance compared to previously reported HTL-free C-PSCs in literature under both standard and indoor lighting conditions. Furthermore, these devices demonstrated potential as self-powered photodetectors, exhibiting a dark current density of 9.84 × 10⁻¹⁰ A cm⁻² and a maximum detectivity of 1.96 × 10¹³ Jones, significantly outperforming most reported carbon-electrode-based photodetectors. This work highlights the effectiveness of the carbon electrode design in enabling high-performance HTL-free carbon-based perovskite photovoltaic and photodetector devices.