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Interface Modeling of Perovskite Polymer Heterostructures for Enhanced Charge Transfer Efficiency in Hybrid Photovoltaic Materials

Somayyeh Alidoust, V. Ongun Özçelik

TL;DR

This study uses density functional theory to analyze MAPbI3/P3HT interfaces under MAI- and PbI_a-terminated MAPbI3 surfaces, revealing termination-dependent interfacial coupling and charge-transfer dynamics. PbI_a termination exhibits stronger hybridization and higher charge transfer, with a more favorable hole-transport pathway, while MAI termination shows weaker coupling but higher hole velocity. Both terminations display type-II, hole-selective band alignment, with PbI_a producing a more pronounced VBM shift. The findings offer design guidelines for engineering perovskite–organic interfaces to optimize hole extraction and improve photovoltaic performance in hybrid PSCs.

Abstract

Perovskite solar cells (PSCs) based on methylammonium lead iodide (MAPbI3) exhibit remarkable photovoltaic performance, where interface engineering with hole transport layers (HTLs) is crucial for optimizing charge transfer and device efficiency. In this work, we present a density functional theory (DFT) study of the MAPbI3/poly(3-hexylthiophene) (P3HT) hybrid interface, focusing on the role of perovskite surface termination in determining interfacial stability and electronic structure. We model MAI- and PbI-terminated MAPbI3 surfaces interfaced with P3HT and compare their interfacial electronic properties. Electronic structure calculations reveal distinct differences in orbital hybridization and band alignment: the MAI/m-P3HT interface exhibits weak coupling, whereas the PbI/m-P3HT interface shows stronger hybridization and enhanced charge transfer. Band alignment confirms type-II, hole-selective character in both cases, with more pronounced valence band maximum adjustment for PbI. Charge difference maps, Bader analysis, and local density of states consistently indicate higher charge transfer and stronger electronic coupling for PbI termination. Electrostatic potential offsets and transport parameters further highlight termination-dependent differences, with lighter effective masses at PbI/m-P3HT and higher hole velocity at MAI/m-P3HT. These findings provide theoretical insight into interfacial charge transport mechanisms and offer guidelines for optimizing perovskite-organic hybrid solar cells.

Interface Modeling of Perovskite Polymer Heterostructures for Enhanced Charge Transfer Efficiency in Hybrid Photovoltaic Materials

TL;DR

This study uses density functional theory to analyze MAPbI3/P3HT interfaces under MAI- and PbI_a-terminated MAPbI3 surfaces, revealing termination-dependent interfacial coupling and charge-transfer dynamics. PbI_a termination exhibits stronger hybridization and higher charge transfer, with a more favorable hole-transport pathway, while MAI termination shows weaker coupling but higher hole velocity. Both terminations display type-II, hole-selective band alignment, with PbI_a producing a more pronounced VBM shift. The findings offer design guidelines for engineering perovskite–organic interfaces to optimize hole extraction and improve photovoltaic performance in hybrid PSCs.

Abstract

Perovskite solar cells (PSCs) based on methylammonium lead iodide (MAPbI3) exhibit remarkable photovoltaic performance, where interface engineering with hole transport layers (HTLs) is crucial for optimizing charge transfer and device efficiency. In this work, we present a density functional theory (DFT) study of the MAPbI3/poly(3-hexylthiophene) (P3HT) hybrid interface, focusing on the role of perovskite surface termination in determining interfacial stability and electronic structure. We model MAI- and PbI-terminated MAPbI3 surfaces interfaced with P3HT and compare their interfacial electronic properties. Electronic structure calculations reveal distinct differences in orbital hybridization and band alignment: the MAI/m-P3HT interface exhibits weak coupling, whereas the PbI/m-P3HT interface shows stronger hybridization and enhanced charge transfer. Band alignment confirms type-II, hole-selective character in both cases, with more pronounced valence band maximum adjustment for PbI. Charge difference maps, Bader analysis, and local density of states consistently indicate higher charge transfer and stronger electronic coupling for PbI termination. Electrostatic potential offsets and transport parameters further highlight termination-dependent differences, with lighter effective masses at PbI/m-P3HT and higher hole velocity at MAI/m-P3HT. These findings provide theoretical insight into interfacial charge transport mechanisms and offer guidelines for optimizing perovskite-organic hybrid solar cells.
Paper Structure (4 sections, 2 equations, 6 figures, 1 table)

This paper contains 4 sections, 2 equations, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. Methods
  3. Results and discussion
  4. Conclusion

Figures (6)

  • Figure 1: (a) 2D periodic structure of P3HT. (b) 3D crystal structure of MAPbI$_3$. (c) Schematic illustration of the MAPbI$_3$/P3HT interface used in this study.
  • Figure 2: (a) MAI, PbI$_a$, and PbI$_b$ terminations of MAPbI$_3$ used for the P3HT interface study. (b) Cohesive energy per atom for each termination; lower values indicate greater stability. (c) Relative total energy versus distance between perovskite surface and m-P3HT; minima mark optimal interface separations. (d,e) Optimized structures of MAPbI$_3$/m-P3HT interfaces for MAI- and PbI$_a$-terminations, respectively..
  • Figure 3: (a, b) Projected band structure and density of states of the MAI/m-P3HT interface (band gap = 0.93 eV), and (c, d) those of the PbI$_a$/m-P3HT interface (band gap = 0.97 eV), illustrating the electronic contributions from each component.
  • Figure 4: Band alignment of the MAI/m-P3HT and PbI$_a$/m-P3HT interfaces, both exhibiting type-II alignment. Gray bars represent the interface band edges, while skyblue and salmon bars indicate the modified perovskite (m-MAPbI$_3$) and modified P3HT (m-P3HT) band edges at the interface, respectively. Cyan and orange bars correspond to the pure perovskite (p-MAPbI$_3$ with MAI and PbI$_a$ terminations) and pure P3HT (p-P3HT), included for comparison.
  • Figure 5: Charge density difference maps showing electron accumulation (yellow) and depletion (cyan) at the (a) MAI/m-P3HT and (b) PbI$_a$/m-P3HT interfaces. LDOS profiles, also shown here, reveal stronger interfacial coupling and charge delocalization in PbI$_a$ termination, supporting higher charge transfer and improved hole extraction.
  • ...and 1 more figures