In situ graphene doping as a route toward efficient perovskite tandem solar cells

Abstract

Tandem solar cells consisting of perovskite and silicon absorbers have the potential to outperform respective state-ofthe-art single junction efficiencies. However, their development requires the gentle deposition of a transparent electrode onto the hybrid perovskite and its organic layers. Implementation of large area graphene obtained by chemical vapour deposition seems to be an excellent solution. In this manuscript we present the impact of graphene on perovskite solar cells and their organic layers. Direct application of graphene on CH3NH3PbI3 is limited by a highly defective interface but insertion of spiro-OMeTAD enables a defect free implementation. Solar cells containing transparent graphene contacts approach identical electrical performance compared to devices with standard Au contacts. Hall-effect measurements of graphene on various organic thin-films, revealed the importance of field effect doping. Gained knowledge enabled the development of a strategy to increase the charge carrier density in graphene by 60 %, while lowering graphene sheet resistance by 24 %. This combined route of spiro-OMeTAD and stabilized adsorbent doping is an important step towards the targeted application in high performance monolithic perovskite/silicon tandem solar cells..

Perovskite/Silicon Tandem Solar Cells: Marriage of Convenience or True Love Story? – An Overview

“…a) Schematic illustration of a semitransparent perovskite solar cell with graphene electrode. Reproduced with permission . b) Transmission spectra of a perovskite cell with graphene transparent electrode.…”

Graphene–Perovskite Solar Cells Exceed 18 % Efficiency: A Stability Study

“…As am atter of fact, the use of graphene and related 2D materials (GRMs) in photovoltaic and in particular in PSCs has been extensively exploited in literature, [51][52][53][54] with the doublef unctiont oi mprove the devicee fficiency and hinder degradation mechanisms. Moreover,t he use of liquid-phasee xfoliated (LPE) graphene flakes, [63] as well as graphene produced by bottom-up approaches, [64][65][66][67] can boost the charge-transport dynamics at the photo electrode (PE). [57] This permits to use GRMs, in the graphene-based oxidized form (GO or RGO), as dopant [58][59][60] and as interlayer, [61,62] with the aim to enhancec harge injection at the counter electrode.…”

Towards a graphene transparent conducting electrode for perovskite/silicon tandem solar cells

“…32,47 In perovskite cells, CVD graphene has been shown to be safely transferrable without damaging the fragile absorber or frequently used hole-transport layers (HTLs), such as spiro-OMeTAD, P3HT, PEDOT:PSS and NiO x , maintaining good, defect-free interfaces. [48][49][50][51][52][53][54][55] Similarly, mono-and multilayerreduced graphene oxide sheets have been effectively deposited directly on perovskite and yielded functioning perovskite cells without a separate HTL. 56 Additionally, graphene flakes have been effectively…”

“…Sheets can be processed and deposited using roll‐to‐roll techniques compatible with perovskite solution and roll‐to‐roll processing 32,47 . In perovskite cells, CVD graphene has been shown to be safely transferrable without damaging the fragile absorber or frequently used hole‐transport layers (HTLs), such as spiro‐OMeTAD, P3HT, PEDOT:PSS and NiO x , maintaining good, defect‐free interfaces 48–55 . Similarly, mono‐ and multilayer‐reduced graphene oxide sheets have been effectively deposited directly on perovskite and yielded functioning perovskite cells without a separate HTL 56 .…”

“…Lang et al demonstrated that CVD graphene TCE integration in perovskite/silicon tandems is possible without damaging the perovskite layer, but its R sheet was too high 48 . Doping graphene with perovskite HTL materials spiro‐OMeTAD, MoO 3, PH3T and PEDOT:PSS in a perovskite cell have been demonstrated, with compatibility possible for perovskite/silicon tandems 49–52,54 . However, these approaches did not lead to a sufficient increase in its carrier concentration, resulting in low efficiencies relative to cells with indium‐based TCEs.…”